diff --git a/README.md b/README.md
index 570c415..34f75f0 100644
--- a/README.md
+++ b/README.md
@@ -16,3 +16,7 @@ spacecraft
 snake
 -----
 ![snake](https://raw.githubusercontent.com/mdibaiee/node-games/master/snake.gif)
+
+tanks
+-----
+![tanks](https://raw.githubusercontent.com/mdibaiee/node-games/master/tanks.gif)
diff --git a/build/classes/interface.js b/build/classes/interface.js
index 7baddb8..e7d44e9 100644
--- a/build/classes/interface.js
+++ b/build/classes/interface.js
@@ -91,6 +91,34 @@ var Interface = (function () {
       }
       listeners.push({ key: key, fn: fn });
     }
+  }, {
+    key: 'line',
+    value: function line(from, to) {
+      var delta = {
+        x: to.x - from.x,
+        y: to.y - from.y
+      };
+
+      var error = 0;
+
+      var deltaerr = Math.abs(delta.y / delta.x);
+
+      var y = from.y;
+
+      for (var x = from.x; x < to.x; x++) {
+        this.cursor.goto(x, y);
+        this.write('.');
+        error += deltaerr;
+
+        while (error >= 0.5) {
+          this.cursor.goto(x, y);
+          this.write('.');
+          y += Math.sign(delta.y);
+
+          error -= 1;
+        }
+      }
+    }
   }, {
     key: 'columns',
     get: function get() {
diff --git a/build/classes/log b/build/classes/log
new file mode 100644
index 0000000..ae06f0c
--- /dev/null
+++ b/build/classes/log
@@ -0,0 +1,5 @@
+0(0) = 0,1
+45(0.7853981633974483) = 0.7071067811865475,0.7071067811865476
+112.5(1.9634954084936207) = 0.9238795325112867,-0.3826834323650897
+157.5(2.748893571891069) = 0.3826834323650899,-0.9238795325112867
+180(3.141592653589793) = 1.2246467991473532e-16,-1
diff --git a/build/classes/tank.js b/build/classes/tank.js
new file mode 100644
index 0000000..999e86d
--- /dev/null
+++ b/build/classes/tank.js
@@ -0,0 +1,176 @@
+'use strict';
+
+var _createClass = (function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; })();
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.Bullet = undefined;
+
+var _unit = require('./unit');
+
+var _unit2 = _interopRequireDefault(_unit);
+
+var _fs = require('fs');
+
+var _fs2 = _interopRequireDefault(_fs);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
+
+function _possibleConstructorReturn(self, call) { if (!self) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return call && (typeof call === "object" || typeof call === "function") ? call : self; }
+
+function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }
+
+var log = function log() {
+  for (var _len = arguments.length, strings = Array(_len), _key = 0; _key < _len; _key++) {
+    strings[_key] = arguments[_key];
+  }
+
+  _fs2.default.appendFileSync(__dirname + '/../log', strings.join(' ') + '\n');
+};
+
+var BULLET_SPEED = 10;
+
+var Tank = (function (_Unit) {
+  _inherits(Tank, _Unit);
+
+  function Tank(ui) {
+    _classCallCheck(this, Tank);
+
+    var _this = _possibleConstructorReturn(this, Object.getPrototypeOf(Tank).call(this, ui));
+
+    _this._angle = 0;
+    _this.bullets = [];
+    _this.health = 100;
+
+    _this.size = { x: 5, y: 3 };
+    return _this;
+  }
+
+  _createClass(Tank, [{
+    key: 'shoot',
+    value: function shoot() {
+      var bullet = new Bullet(this.output);
+      bullet.go(this.x + 2, this.y - 2);
+      bullet.velocity = this.normalize();
+
+      log(this.angle, '(' + this._angle + ') =', bullet.velocity.join(','));
+
+      this.bullets.push(bullet);
+    }
+  }, {
+    key: 'draw',
+    value: function draw() {
+      if (this.dead) return;
+
+      var x = this.x;
+      var y = this.y;
+
+      if (this.color && this.color[0] === '#') {
+        this.output.cursor.hex(this.color);
+      } else if (this.color) {
+        this.output.cursor[this.color]();
+      }
+      if (this.bold) this.output.cursor.bold();
+
+      x = Math.round(x) + 2;
+      y = Math.round(y) - 2;
+
+      var cannon = undefined;
+      if (this.angle < 35) cannon = '_';else if (this.angle < 70) cannon = '/';else if (this.angle < 115) cannon = '|';else if (this.angle < 160) cannon = '\\';else cannon = '_';
+
+      this.output.cursor.goto(x + 2, y - 2);
+      this.output.write(cannon);
+      this.output.cursor.goto(x, y - 1);
+      this.output.write('.===.');
+      this.output.cursor.goto(x, y);
+      this.output.write('o===o');
+      this.output.cursor.reset();
+    }
+  }, {
+    key: 'normalize',
+    value: function normalize() {
+      return [Math.cos(this._angle), Math.sin(this._angle) * -1];
+    }
+  }, {
+    key: 'angle',
+    set: function set(deg) {
+      if (deg < 0) deg = 0;
+      if (deg > 180) deg = 180;
+
+      this._angle = _radian(deg);
+    },
+    get: function get() {
+      return _degree(this._angle);
+    }
+  }], [{
+    key: 'radian',
+    value: function radian(deg) {
+      return _radian(deg);
+    }
+  }, {
+    key: 'degree',
+    value: function degree(rad) {
+      return _degree(rad);
+    }
+  }]);
+
+  return Tank;
+})(_unit2.default);
+
+exports.default = Tank;
+
+var Bullet = exports.Bullet = (function (_Unit2) {
+  _inherits(Bullet, _Unit2);
+
+  function Bullet(ui) {
+    _classCallCheck(this, Bullet);
+
+    var _this2 = _possibleConstructorReturn(this, Object.getPrototypeOf(Bullet).call(this, ui));
+
+    _this2.velocity = [0, 0];
+
+    _this2.shape = '•';
+    _this2.color = 'red';
+
+    _this2.dieOnExit = true;
+
+    _this2.gravity = [0.8, 0.8];
+    _this2.acceleration = [0, 0.015];
+    return _this2;
+  }
+
+  _createClass(Bullet, [{
+    key: 'speed',
+    value: function speed() {
+      this.velocity[0] += this.acceleration[0];
+      this.velocity[1] += this.acceleration[1];
+
+      var x = this.velocity[0] * this.gravity[0];
+      var y = this.velocity[1] * this.gravity[1];
+      return [x, y];
+    }
+  }, {
+    key: 'collides',
+    value: function collides(target) {
+      var targetX = Math.round(target.x);
+      var targetY = Math.round(target.y);
+      var x = Math.round(this.x);
+      var y = Math.round(this.y);
+
+      return x > targetX - target.size.x && x < targetX + target.size.x && y > targetY - target.size.y && y < targetY + target.size.y;
+    }
+  }]);
+
+  return Bullet;
+})(_unit2.default);
+
+function _radian(deg) {
+  return deg * Math.PI / 180;
+}
+
+function _degree(rad) {
+  return rad * 180 / Math.PI;
+}
diff --git a/build/classes/unit.js b/build/classes/unit.js
index 777f077..2728e25 100644
--- a/build/classes/unit.js
+++ b/build/classes/unit.js
@@ -87,7 +87,7 @@ var Unit = (function () {
   }, {
     key: 'health',
     set: function set(value) {
-      this._health = Math.min(0, value);
+      this._health = Math.max(0, value);
 
       if (this.health === 0) {
         this.dead = true;
diff --git a/build/log b/build/log
index e69de29..3a9143c 100644
--- a/build/log
+++ b/build/log
@@ -0,0 +1,174 @@
+0 (0) =  0,1
+45 (0.7853981633974483) =  0.7071067811865475,0.7071067811865476
+45 (0.7853981633974483) =  0.7071067811865475,0.7071067811865476
+90 (1.5707963267948966) =  1,6.123233995736766e-17
+135 (2.356194490192345) =  0.7071067811865476,-0.7071067811865475
+180 (3.141592653589793) =  1.2246467991473532e-16,-1
+0 (0) = 1,0
+45 (0.7853981633974483) = 0.7071067811865476,0.7071067811865475
+90 (1.5707963267948966) = 6.123233995736766e-17,1
+135 (2.356194490192345) = -0.7071067811865475,0.7071067811865476
+180 (3.141592653589793) = -1,1.2246467991473532e-16
+0 (0) = -1,0
+45 (0.7853981633974483) = -0.7071067811865476,-0.7071067811865475
+90 (1.5707963267948966) = -6.123233995736766e-17,-1
+0 (0) = 1,0
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+90 (1.5707963267948966) = 6.123233995736766e-17,-1
+135 (2.356194490192345) = -0.7071067811865475,-0.7071067811865476
+180 (3.141592653589793) = -1,-1.2246467991473532e-16
+0 (0) = 1,0
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+90 (1.5707963267948966) = 6.123233995736766e-17,-1
+135 (2.356194490192345) = -0.7071067811865475,-0.7071067811865476
+180 (3.141592653589793) = -1,-1.2246467991473532e-16
+112.5 (1.9634954084936207) = -0.3826834323650897,-0.9238795325112867
+112.5 (1.9634954084936207) = -0.3826834323650897,-0.9238795325112867
+112.5 (1.9634954084936207) = -0.3826834323650897,-0.9238795325112867
+90 (1.5707963267948966) = 6.123233995736766e-17,-1
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+22.5 (0.39269908169872414) = 0.9238795325112867,-0.3826834323650898
+22.5 (0.39269908169872414) = 0.9238795325112867,-0.3826834323650898
+45 (0.7853981633974483) = 0.7071067811865476,-0.7071067811865475
+0 (0) = 1,0
+22.5 (0.39269908169872414) = 0.9238795325112867,-0.3826834323650898
+53.999999999999964 (0.9424777960769373) = 0.5877852522924737,-0.809016994374947
+0 (0) = 1,0
+54.999999999999964 (0.9599310885968807) = 0.5735764363510466,-0.8191520442889915
+180 (3.141592653589793) = -1,-1.2246467991473532e-16
+32.99999999999997 (0.5759586531581282) = 0.8386705679454243,-0.5446390350150266
+170.00000000000003 (2.967059728390361) = -0.9848077530122081,-0.17364817766692983
+42.99999999999997 (0.7504915783575612) = 0.7313537016191709,-0.6819983600624981
+170.00000000000003 (2.967059728390361) = -0.9848077530122081,-0.17364817766692983
+42.99999999999997 (0.7504915783575612) = 0.7313537016191709,-0.6819983600624981
+170.00000000000003 (2.967059728390361) = -0.9848077530122081,-0.17364817766692983
+45.99999999999997 (0.802851455917391) = 0.6946583704589977,-0.7193398003386507
+170.00000000000003 (2.967059728390361) = -0.9848077530122081,-0.17364817766692983
+35 (0.6108652381980153) = 0.8191520442889918,-0.573576436351046
+49.99999999999997 (0.8726646259971643) = 0.6427876096865397,-0.7660444431189777
+162.00000000000009 (2.827433388230815) = -0.951056516295154,-0.3090169943749463
+48.99999999999997 (0.8552113334772209) = 0.6560590289905077,-0.7547095802227716
+167.00000000000009 (2.914699850830532) = -0.9743700647852356,-0.22495105434386348
+46.999999999999964 (0.8203047484373343) = 0.6819983600624989,-0.73135370161917
+48.99999999999997 (0.8552113334772209) = 0.6560590289905077,-0.7547095802227716
+45.999999999999986 (0.8028514559173914) = 0.6946583704589975,-0.7193398003386511
+162.00000000000009 (2.827433388230815) = -0.951056516295154,-0.3090169943749463
+45.999999999999986 (0.8028514559173914) = 0.6946583704589975,-0.7193398003386511
+162.00000000000009 (2.827433388230815) = -0.951056516295154,-0.3090169943749463
+45.999999999999986 (0.8028514559173914) = 0.6946583704589975,-0.7193398003386511
+162.00000000000009 (2.827433388230815) = -0.951056516295154,-0.3090169943749463
+45.999999999999986 (0.8028514559173914) = 0.6946583704589975,-0.7193398003386511
+162.00000000000009 (2.827433388230815) = -0.951056516295154,-0.3090169943749463
+45.999999999999986 (0.8028514559173914) = 0.6946583704589975,-0.7193398003386511
+162.00000000000009 (2.827433388230815) = -0.951056516295154,-0.3090169943749463
+45.999999999999986 (0.8028514559173914) = 0.6946583704589975,-0.7193398003386511
+162.00000000000009 (2.827433388230815) = -0.951056516295154,-0.3090169943749463
+45.999999999999986 (0.8028514559173914) = 0.6946583704589975,-0.7193398003386511
+162.00000000000009 (2.827433388230815) = -0.951056516295154,-0.3090169943749463
+45.999999999999986 (0.8028514559173914) = 0.6946583704589975,-0.7193398003386511
+162.00000000000009 (2.827433388230815) = -0.951056516295154,-0.3090169943749463
+45.999999999999986 (0.8028514559173914) = 0.6946583704589975,-0.7193398003386511
+162.00000000000009 (2.827433388230815) = -0.951056516295154,-0.3090169943749463
+20.999999999999986 (0.366519142918809) = 0.9335804264972019,-0.35836794954530005
+46.999999999999986 (0.8203047484373346) = 0.6819983600624987,-0.7313537016191702
+147 (2.5656340004316647) = -0.8386705679454242,-0.5446390350150269
+26.999999999999993 (0.47123889803846886) = 0.8910065241883679,-0.4539904997395467
+147 (2.5656340004316647) = -0.8386705679454242,-0.5446390350150269
+10.99999999999999 (0.19198621771937607) = 0.981627183447664,-0.19080899537654464
+147 (2.5656340004316647) = -0.8386705679454242,-0.5446390350150269
+10.99999999999999 (0.19198621771937607) = 0.981627183447664,-0.19080899537654464
+147 (2.5656340004316647) = -0.8386705679454242,-0.5446390350150269
+10.99999999999999 (0.19198621771937607) = 0.981627183447664,-0.19080899537654464
+147 (2.5656340004316647) = -0.8386705679454242,-0.5446390350150269
+10.99999999999999 (0.19198621771937607) = 0.981627183447664,-0.19080899537654464
+147 (2.5656340004316647) = -0.8386705679454242,-0.5446390350150269
+10.99999999999999 (0.19198621771937607) = 0.981627183447664,-0.19080899537654464
+147 (2.5656340004316647) = -0.8386705679454242,-0.5446390350150269
+10.99999999999999 (0.19198621771937607) = 0.981627183447664,-0.19080899537654464
+147 (2.5656340004316647) = -0.8386705679454242,-0.5446390350150269
+10.99999999999999 (0.19198621771937607) = 0.981627183447664,-0.19080899537654464
+147 (2.5656340004316647) = -0.8386705679454242,-0.5446390350150269
+10.99999999999999 (0.19198621771937607) = 0.981627183447664,-0.19080899537654464
+147 (2.5656340004316647) = -0.8386705679454242,-0.5446390350150269
+10.99999999999999 (0.19198621771937607) = 0.981627183447664,-0.19080899537654464
+48.99999999999998 (0.8552113334772211) = 0.6560590289905076,-0.7547095802227717
+10 (0.17453292519943295) = 0.984807753012208,-0.17364817766693033
+0 (0) = 1,0
+10 (0.17453292519943295) = 0.984807753012208,-0.17364817766693033
+0 (0) = 1,0
+10 (0.17453292519943295) = 0.984807753012208,-0.17364817766693033
+0 (0) = 1,0
+10 (0.17453292519943295) = 0.984807753012208,-0.17364817766693033
+0 (0) = 1,0
+10 (0.17453292519943295) = 0.984807753012208,-0.17364817766693033
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+49.99999999999997 (0.8726646259971643) = 0.6427876096865397,-0.7660444431189777
+19.999999999999986 (0.3490658503988657) = 0.9396926207859084,-0.3420201433256685
+0 (0) = 1,0
+19.999999999999986 (0.3490658503988657) = 0.9396926207859084,-0.3420201433256685
+0 (0) = 1,0
+19.999999999999986 (0.3490658503988657) = 0.9396926207859084,-0.3420201433256685
+0 (0) = 1,0
+0 (0) = 1,0
+0 (0) = 1,0
+180 (3.141592653589793) = -1,-1.2246467991473532e-16
+180 (3.141592653589793) = -1,-1.2246467991473532e-16
+180 (3.141592653589793) = -1,-1.2246467991473532e-16
+180 (3.141592653589793) = -1,-1.2246467991473532e-16
+180 (3.141592653589793) = -1,-1.2246467991473532e-16
+180 (3.141592653589793) = -1,-1.2246467991473532e-16
+0 (0) = 1,0
+0 (0) = 1,0
+47.99999999999998 (0.8377580409572778) = 0.6691306063588585,-0.743144825477394
+134.99999999999991 (2.3561944901923435) = -0.7071067811865466,-0.7071067811865486
diff --git a/build/snake.js b/build/snake.js
index 60a7d74..4677856 100644
--- a/build/snake.js
+++ b/build/snake.js
@@ -10,10 +10,6 @@ var _interface = require('./classes/interface');
 
 var _interface2 = _interopRequireDefault(_interface);
 
-var _fs = require('fs');
-
-var _fs2 = _interopRequireDefault(_fs);
-
 function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
 
 var FRAME = 100;
diff --git a/build/tanks.js b/build/tanks.js
new file mode 100644
index 0000000..6eb279e
--- /dev/null
+++ b/build/tanks.js
@@ -0,0 +1,156 @@
+'use strict';
+
+var _unit = require('./classes/unit');
+
+var _unit2 = _interopRequireDefault(_unit);
+
+var _tank = require('./classes/tank');
+
+var _tank2 = _interopRequireDefault(_tank);
+
+var _interface = require('./classes/interface');
+
+var _interface2 = _interopRequireDefault(_interface);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+var FRAME = 50;
+var ui = new _interface2.default();
+var immoblize = false;
+
+var one = new _tank2.default(ui);
+one.go(10, ui.rows);
+
+var two = new _tank2.default(ui);
+two.go(ui.columns - 10, ui.rows);
+
+var stop = false;
+
+function loop() {
+  if (stop) return;
+
+  ui.clear();
+
+  if (one.dead || two.dead) {
+    var num = one.dead ? '2' : '1';
+    var msg = 'Player ' + num + ' won!';
+    ui.cursor.red();
+    ui.cursor.bold();
+
+    ui.cursor.goto(ui.center.x - msg.length / 2, ui.center.y);
+    ui.write(msg);
+
+    stop = true;
+    return;
+  }
+
+  one.draw();
+  one.bullets.forEach(function (bullet, i) {
+    if (bullet.dead) {
+      immoblize = false;
+      one.bullets.splice(i, 1);
+      return;
+    }
+    bullet.move();
+    bullet.draw();
+
+    if (bullet.collides(two)) {
+      two.health -= 10;
+      bullet.dead = true;
+    }
+  });
+
+  ui.cursor.goto(0, 1);
+  if (turn() === one) ui.cursor.hex('#54ffff');
+  ui.write('Player 1');
+  ui.cursor.reset();
+  ui.cursor.goto(0, 2);
+  ui.write('Health: ' + one.health);
+  ui.cursor.goto(0, 3);
+  ui.write('Angle: ' + parseInt(one.angle));
+
+  two.draw();
+  two.bullets.forEach(function (bullet, i) {
+    if (bullet.dead) {
+      immoblize = false;
+      two.bullets.splice(i, 1);
+      return;
+    }
+    bullet.move();
+    bullet.draw();
+
+    if (bullet.collides(one)) {
+      one.health -= 10;
+      bullet.dead = true;
+    }
+  });
+
+  ui.cursor.goto(ui.output.columns - 10, 1);
+  if (turn() === two) ui.cursor.hex('#54ffff');
+  ui.write('Player 2');
+  ui.cursor.reset();
+  ui.cursor.goto(ui.output.columns - 10, 2);
+  ui.write('Health: ' + two.health);
+  ui.cursor.goto(ui.output.columns - 10, 3);
+  ui.write('Angle: ' + parseInt(two.angle));
+
+  setTimeout(loop, FRAME);
+}
+
+loop();
+
+ui.onKey('down', function () {
+  if (immoblize) return;
+
+  turn().angle -= 1;
+});
+
+ui.onKey('up', function () {
+  if (immoblize) return;
+
+  turn().angle += 1;
+});
+
+ui.onKey('left', function () {
+  if (immoblize) return;
+
+  turn().x -= 1;
+});
+
+ui.onKey('right', function () {
+  if (immoblize) return;
+
+  turn().x += 1;
+});
+
+ui.onKey('space', function () {
+  if (immoblize) return;
+
+  turn().shoot();
+
+  immoblize = true;
+  TURN = !TURN;
+});
+
+ui.onKey(function () {
+  if (one.dead || two.dead) {
+    one.go(10, ui.rows);
+    two.go(ui.columns - 10, ui.rows);
+
+    one.health = 100;
+    two.health = 100;
+
+    one.dead = false;
+    two.dead = false;
+
+    stop = false;
+
+    loop();
+  }
+});
+
+var TURN = true;
+function turn() {
+  if (TURN) return one;
+  return two;
+}
diff --git a/package.json b/package.json
index e2ffd06..562fc9e 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "node-games",
-  "version": "2.1.0",
+  "version": "3.0.0",
   "description": "Simple node console games",
   "main": "index.js",
   "scripts": {
diff --git a/src/classes/interface.js b/src/classes/interface.js
index 4052876..b8f33fc 100644
--- a/src/classes/interface.js
+++ b/src/classes/interface.js
@@ -74,4 +74,31 @@ export default class Interface {
       y: this.output.rows / 2
     }
   }
+
+  line(from, to) {
+    let delta = {
+      x: to.x - from.x,
+      y: to.y - from.y
+    }
+
+    let error = 0;
+
+    let deltaerr = Math.abs(delta.y / delta.x);
+
+    let { y } = from;
+
+    for (let x = from.x; x < to.x; x++) {
+      this.cursor.goto(x, y);
+      this.write('.');
+      error += deltaerr;
+
+      while (error >= 0.5) {
+        this.cursor.goto(x, y);
+        this.write('.');
+        y += Math.sign(delta.y);
+
+        error -= 1;
+      }
+    }
+  }
 }
diff --git a/src/classes/tank.js b/src/classes/tank.js
new file mode 100644
index 0000000..e642300
--- /dev/null
+++ b/src/classes/tank.js
@@ -0,0 +1,127 @@
+import Unit from './unit';
+import fs from 'fs';
+
+let log = (...strings) => {
+  fs.appendFileSync(__dirname + '/../log', strings.join(' ') + '\n');
+}
+
+const BULLET_SPEED = 10;
+
+export default class Tank extends Unit {
+  constructor(ui) {
+    super(ui);
+
+    this._angle = 0;
+    this.bullets = [];
+    this.health = 100;
+
+    this.size = { x: 5, y: 3 };
+  }
+
+  set angle(deg) {
+    if (deg < 0) deg = 0;
+    if (deg > 180) deg = 180;
+
+    this._angle = radian(deg);
+  }
+
+  get angle() {
+    return degree(this._angle);
+  }
+
+  shoot() {
+    let bullet = new Bullet(this.output);
+    bullet.go(this.x + 2, this.y - 2);
+    bullet.velocity = this.normalize();
+
+    log(this.angle, '(' + this._angle + ') =', bullet.velocity.join(','));
+
+    this.bullets.push(bullet);
+  }
+
+  draw() {
+    if (this.dead) return;
+
+    let { x, y } = this;
+    if (this.color && this.color[0] === '#') {
+      this.output.cursor.hex(this.color);
+    } else if (this.color) {
+      this.output.cursor[this.color]();
+    }
+    if (this.bold) this.output.cursor.bold();
+
+
+    x = Math.round(x) + 2;
+    y = Math.round(y) - 2;
+
+    let cannon;
+    if (this.angle < 35) cannon = '_';
+    else if (this.angle < 70) cannon = '/';
+    else if (this.angle < 115) cannon = '|';
+    else if (this.angle < 160) cannon = '\\';
+    else cannon = '_';
+
+    this.output.cursor.goto(x + 2, y - 2);
+    this.output.write(cannon);
+    this.output.cursor.goto(x, y - 1);
+    this.output.write('.===.');
+    this.output.cursor.goto(x, y);
+    this.output.write('o===o');
+    this.output.cursor.reset();
+  }
+
+  normalize() {
+    return [Math.cos(this._angle), Math.sin(this._angle) * -1];
+  }
+
+  static radian(deg) {
+    return radian(deg);
+  }
+
+  static degree(rad) {
+    return degree(rad);
+  }
+}
+
+export class Bullet extends Unit {
+  constructor(ui) {
+    super(ui);
+
+    this.velocity = [0, 0];
+
+    this.shape = '•';
+    this.color = 'red';
+
+    this.dieOnExit = true;
+
+    this.gravity = [0.8, 0.8];
+    this.acceleration = [0, 0.015];
+  }
+
+  speed() {
+    this.velocity[0] += this.acceleration[0];
+    this.velocity[1] += this.acceleration[1];
+
+    let x = this.velocity[0] * this.gravity[0];
+    let y = this.velocity[1] * this.gravity[1];
+    return [x, y];
+  }
+
+  collides(target) {
+    let targetX = Math.round(target.x);
+    let targetY = Math.round(target.y);
+    let x = Math.round(this.x);
+    let y = Math.round(this.y);
+
+    return x > targetX - target.size.x && x < targetX + target.size.x &&
+           y > targetY - target.size.y && y < targetY + target.size.y;
+  }
+}
+
+function radian(deg) {
+  return deg * Math.PI / 180;
+}
+
+function degree(rad) {
+  return rad * 180 / Math.PI;
+}
diff --git a/src/classes/unit.js b/src/classes/unit.js
index bdbb8ab..ecafbe1 100644
--- a/src/classes/unit.js
+++ b/src/classes/unit.js
@@ -8,7 +8,7 @@ export default class Unit {
   }
 
   set health(value) {
-    this._health = Math.min(0, value);
+    this._health = Math.max(0, value);
 
     if (this.health === 0) {
       this.dead = true;
diff --git a/src/snake.js b/src/snake.js
index 1226e8d..94f48c8 100644
--- a/src/snake.js
+++ b/src/snake.js
@@ -1,6 +1,5 @@
 import Unit from './classes/unit';
 import Interface from './classes/interface';
-import fs from 'fs';
 
 let FRAME = 100;
 let ui = new Interface();
diff --git a/src/tanks.js b/src/tanks.js
new file mode 100644
index 0000000..bb9c693
--- /dev/null
+++ b/src/tanks.js
@@ -0,0 +1,144 @@
+import Unit from './classes/unit';
+import Tank from './classes/tank';
+import Interface from './classes/interface';
+
+let FRAME = 50;
+let ui = new Interface();
+let immoblize = false;
+
+let one = new Tank(ui);
+one.go(10, ui.rows);
+
+let two = new Tank(ui);
+two.go(ui.columns - 10, ui.rows);
+
+let stop = false;
+
+function loop() {
+  if (stop) return;
+
+  ui.clear();
+
+  if (one.dead || two.dead) {
+    let num = one.dead ? '2' : '1';
+    const msg = `Player ${num} won!`;
+    ui.cursor.red();
+    ui.cursor.bold();
+
+    ui.cursor.goto(ui.center.x - msg.length / 2, ui.center.y);
+    ui.write(msg);
+
+    stop = true;
+    return;
+  }
+
+  one.draw();
+  one.bullets.forEach((bullet, i) => {
+    if (bullet.dead) {
+      immoblize = false;
+      one.bullets.splice(i, 1);
+      return;
+    }
+    bullet.move();
+    bullet.draw();
+
+    if (bullet.collides(two)) {
+      two.health -= 10;
+      bullet.dead = true;
+    }
+  });
+
+  ui.cursor.goto(0, 1);
+  if (turn() === one) ui.cursor.hex('#54ffff');
+  ui.write('Player 1');
+  ui.cursor.reset();
+  ui.cursor.goto(0, 2);
+  ui.write('Health: ' + one.health);
+  ui.cursor.goto(0, 3);
+  ui.write('Angle: ' + parseInt(one.angle));
+
+  two.draw();
+  two.bullets.forEach((bullet, i) => {
+    if (bullet.dead) {
+      immoblize = false;
+      two.bullets.splice(i, 1);
+      return;
+    }
+    bullet.move();
+    bullet.draw();
+
+    if (bullet.collides(one)) {
+      one.health -= 10;
+      bullet.dead = true;
+    }
+  });
+
+  ui.cursor.goto(ui.output.columns - 10, 1);
+  if (turn() === two) ui.cursor.hex('#54ffff');
+  ui.write('Player 2');
+  ui.cursor.reset();
+  ui.cursor.goto(ui.output.columns - 10, 2);
+  ui.write('Health: ' + two.health);
+  ui.cursor.goto(ui.output.columns - 10, 3);
+  ui.write('Angle: ' + parseInt(two.angle));
+
+  setTimeout(loop, FRAME);
+}
+
+loop();
+
+ui.onKey('down', () => {
+  if (immoblize) return;
+
+  turn().angle -= 1;
+})
+
+ui.onKey('up', () => {
+  if (immoblize) return;
+
+  turn().angle += 1;
+})
+
+ui.onKey('left', () => {
+  if (immoblize) return;
+
+  turn().x -= 1;
+});
+
+ui.onKey('right', () => {
+  if (immoblize) return;
+
+  turn().x += 1;
+});
+
+ui.onKey('space', () => {
+  if (immoblize) return;
+
+  turn().shoot();
+
+  immoblize = true;
+  TURN = !TURN;
+});
+
+ui.onKey(() => {
+  if (one.dead || two.dead) {
+    one.go(10, ui.rows);
+    two.go(ui.columns - 10, ui.rows);
+
+    one.health = 100;
+    two.health = 100;
+
+    one.dead = false;
+    two.dead = false;
+
+    stop = false;
+
+    loop();
+  }
+})
+
+let TURN = true;
+function turn() {
+  if (TURN) return one;
+  return two;
+}
diff --git a/tanks.gif b/tanks.gif
new file mode 100644
index 0000000..d6e3a1b
Binary files /dev/null and b/tanks.gif differ