diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..6f92bec
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+# Ignore NXT executable files, RIC edit data and Gedit backup files.
+*.rxe
+*.RPA
+*~
diff --git a/LICENSE b/LICENSE
index e69de29..4869415 100644
--- a/LICENSE
+++ b/LICENSE
@@ -0,0 +1,25 @@
+A Space Invaders clone for the Mindstorms NXT.
+
+Copyright (c) 2013, Miguel Angel Astor Romero
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+  *) Redistributions of source code must retain the above
+     copyright notice, this list of conditions and the following disclaimer.
+  *) Redistributions in binary form must reproduce the above copyright notice,
+     this list of conditions and the following disclaimer in the documentation
+     and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITSOR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..f7007b9
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,5 @@
+all: NXTInvaders.nxc
+	nbc NXTInvaders.nxc -O=NXTInvaders.rxe -sm+ -d -S=usb
+
+clean:
+	rm -f NXTInvaders.rxe
diff --git a/NXTInvaders.nxc b/NXTInvaders.nxc
new file mode 100644
index 0000000..b038c41
--- /dev/null
+++ b/NXTInvaders.nxc
@@ -0,0 +1,449 @@
+/*------------------------------------------------------------------------------
+; File :          NXTInvaders.nxc
+; Description :   A Space Invaders clone for the Mindstorms NXT.
+; Programmed by : Miguel Angel Astor, sonofgrendel@gmail.com
+; Version:        1.0
+; Date:           8/13/2013
+;-----------------------------------------------------------------------------*/
+
+#download "ship.ric"
+#download "splash.ric"
+#download "invader.ric"
+#download "victory.ric"
+#download "defeat.ric"
+#define X_MAX 99
+#define Y_MAX 63
+#define X_MID (X_MAX + 1) / 2
+#define Y_MID (Y_MAX + 1) / 2
+#define DRAW_PARAMS DRAW_OPT_NORMAL | DRAW_OPT_LOGICAL_XOR | DRAW_OPT_FILL_SHAPE
+#define ALIEN_WIDTH 11
+#define BASE_ALIEN_X 2
+#define BASE_ALIEN_Y 32
+#define ALIENS 6
+
+/*******************
+ * Data structures *
+ *******************/
+struct PLAYER_T{
+  int x;
+  int lives;
+  int score;
+};
+
+struct BULLET_T{
+  int x, y;
+  bool alive;
+};
+
+struct ALIEN_T{
+  int x, y;
+  bool alive;
+};
+
+/****************
+ * Global data. *
+ ****************/
+const int alien_update_speed[] = {50, 72, 95,
+                                  118, 140, 163,
+                                  186, 209, 231,
+                                  254, 277, 300 };
+int dead_aliens;
+bool victory;
+// keys[0] -> Left button; keys[1] -> Right button; keys[2] -> Center button.
+bool keys[3];
+// State: 0 -> Splash screen; 1 -> Game; 2 -> Hall of fame screen.
+int state, alien_frame, alien_x_offset;
+bool alien_x_forward, done;
+long then, then2;
+PLAYER_T player;
+BULLET_T p_bullets[3];
+ALIEN_T aliens1[ALIENS];
+ALIEN_T aliens2[ALIENS];
+BULLET_T a_bullets1[ALIENS];
+BULLET_T a_bullets2[ALIENS];
+
+/*******************
+ * Game functions. *
+ *******************/
+ /**
+  * Catch the 3 possible player inputs.
+  */
+void input(){
+  if(ButtonPressed(BTNLEFT, false)){
+    keys[0] = true;
+  }else{
+    keys[0] = false;
+  }
+
+  if(ButtonPressed(BTNRIGHT, false)){
+    keys[1] = true;
+  }else{
+    keys[1] = false;
+  }
+
+  if(ButtonPressed(BTNCENTER, false)){
+    keys[2] = true;
+  }else{
+    keys[2] = false;
+  }
+}
+
+/**
+ * Processes player input, moves game objects and updates the game's state.
+ */
+void update(){
+  long now, delta_t, fire;
+  
+  if(state == 0){
+    if(keys[2]){
+      state = 1;
+    }
+  }else if(state == 1){
+    // Move the player.
+    if(keys[0]){
+      if(player.x - 1 >= 3){
+        player.x -= 1;
+      }
+    }
+    if(keys[1]){
+      if(player.x + 1 <= X_MAX - 4){
+        player.x += 1;
+      }
+    }
+
+    // If the center button was pressed, fire a bullet.
+    if(keys[2]){
+      now = CurrentTick();
+      delta_t = now - then;
+      if(delta_t >= 500){
+        // One bullet every 500 miliseconds.
+        for(int i = 0; i < 3; i++){
+          if(!p_bullets[i].alive){
+            p_bullets[i].x = player.x;
+            p_bullets[i].y = 0;
+            p_bullets[i].alive = true;
+            PlayTone(262, 100);
+            break;
+          }
+        }
+        then = now;
+      }
+    }
+
+    // Update the player's bullets.
+    for(int i = 0; i < 3; i++){
+      if(p_bullets[i].alive){
+        p_bullets[i].y += 1;
+        if(p_bullets[i].y >= Y_MAX + 2){
+          p_bullets[i].alive = false;
+        }
+      }
+    }
+
+    // Update the aliens.
+    now = CurrentTick();
+    delta_t = now - then2;
+    if(delta_t >= alien_update_speed[11 - dead_aliens]){
+      // Change the frame.
+      if(alien_frame == 0){
+        alien_frame = 11;
+      }else{
+        alien_frame = 0;
+      }
+      
+      // Move in the correct direction.
+      if(alien_x_forward){
+        alien_x_offset += 1;
+        if(alien_x_offset >= 15){
+          // Change direction 2 pixels before the edge of the screen.
+          alien_x_offset -= 1;
+          alien_x_forward = false;
+        }
+      }else{
+        alien_x_offset -= 1;
+        if(alien_x_offset <= 0){
+          // Change direction 2 pixels before the edge of the screen.
+          alien_x_offset += 1;
+          alien_x_forward = true;
+        }
+      }
+    
+      // Fire on the player.
+      for(int i = 0; i < ALIENS; i++){
+        // First row.
+        if(aliens1[i].alive && !a_bullets1[i].alive){
+          fire = rand() % 100;
+          if(fire < 25){
+            // 0.25 probability of firing.
+            a_bullets1[i].alive = true;
+            a_bullets1[i].x = aliens1[i].x + alien_x_offset + 5;
+            a_bullets1[i].y = aliens1[i].y;
+            PlayTone(400, 100);
+          }
+        }
+        // Second row.
+        if(aliens2[i].alive && !a_bullets2[i].alive){
+          fire = rand() % 100;
+          if(fire > 75){
+            // 0.25 probability of firing.
+            a_bullets2[i].alive = true;
+            a_bullets2[i].x = aliens2[i].x + alien_x_offset + 5;
+            a_bullets2[i].y = aliens2[i].y;
+            PlayTone(400, 100);
+          }
+        }
+      }
+      then2 = now;
+    }
+
+    // Update the alien's bullets.
+    for(int i = 0; i < ALIENS; i++){
+      // First row.      
+      if(a_bullets1[i].alive){
+        a_bullets1[i].y -= 1;
+        if(a_bullets1[i].y < -2){
+          a_bullets1[i].alive = false;
+        }
+      }
+      // Second row.
+      if(a_bullets2[i].alive){
+        a_bullets2[i].y -= 1;
+        if(a_bullets2[i].y < -2){
+          a_bullets2[i].alive = false;
+        }
+      }
+    }
+
+    // Check if any bullet shot by the player hit an alien.
+    for(int i = 0; i < 3; i++){
+      if(p_bullets[i].alive){
+        if(p_bullets[i].y >= 22 && p_bullets[i].y <= 30){
+          // Check the second row first.
+          for(int j = 0; j < ALIENS; j++){
+            if(aliens2[j].alive){
+              if(p_bullets[i].x >= aliens2[j].x + alien_x_offset &&
+                 p_bullets[i].x <= aliens2[j].x + alien_x_offset + 11){
+                aliens2[j].alive = false;
+                p_bullets[i].alive = false;
+                player.score += 100;
+                dead_aliens += 1;
+                PlayTone(100, 250);
+                break;
+              }
+            }
+          }
+        }else if(p_bullets[i].y >= 32 && p_bullets[i].y <= 40){
+          // Check the first row last.
+          for(int j = 0; j < ALIENS; j++){
+            if(aliens1[j].alive){
+              if(p_bullets[i].x >= aliens1[j].x + alien_x_offset &&
+                 p_bullets[i].x <= aliens1[j].x + alien_x_offset + 11){
+                aliens1[j].alive = false;
+                p_bullets[i].alive = false;
+                player.score += 150;
+                dead_aliens += 1;
+                PlayTone(100, 250);
+                break;
+              }
+            }
+          }
+        }
+      }
+    }
+
+    // Check alien bullet collisions with player.
+    // First row.
+    for(int i = 0; i < ALIENS; i++){
+      if(a_bullets1[i].alive && a_bullets1[i].y <= 2){
+        if(a_bullets1[i].x >= player.x - 3 && a_bullets1[i].x <= player.x + 4){
+          // If the bullet hit the player, reset the game.
+          player.x = X_MID;
+          player.lives -= 1;
+          alien_x_offset = 0;
+          alien_x_forward = true;
+          for(int j = 0; j < ALIENS; j++){
+            a_bullets1[i].alive = false;
+            a_bullets2[i].alive = false;
+          }
+          PlayTone(100, 250);
+          break;
+        }
+      }
+    }
+    
+    // Second row
+    for(int i = 0; i < ALIENS; i++){
+      if(a_bullets2[i].alive && a_bullets2[i].y <= 2){
+        if(a_bullets2[i].x >= player.x - 3 && a_bullets2[i].x <= player.x + 4){
+          // If the bullet hit the player, reset the game.
+          player.x = X_MID;
+          player.lives -= 1;
+          alien_x_offset = 0;
+          alien_x_forward = true;
+          for(int j = 0; j < ALIENS; j++){
+            a_bullets1[i].alive = false;
+            a_bullets2[i].alive = false;
+          }
+          PlayTone(100, 250);
+          break;
+        }
+      }
+    }
+
+    // Check victory/defeat conditions.
+    if(dead_aliens == 12){
+      state = 2;
+      victory = true;
+      PlayTone(500, 1000);
+      ClearScreen();
+    }else if(player.lives < 0){
+      state = 2;
+      victory = false;
+      PlayTone(100, 1000);
+      ClearScreen();
+    }
+  }else{
+    if(keys[2]){
+      done = true;
+    }
+  }
+}
+
+/**
+ * Draws all game objects to the LCD screen of the robot.
+ */
+void render(){
+  int params[3] = {0, 0, 0};
+  if(state == 0){
+    // Render the splash screen.
+    GraphicOut(0, 0, "splash.ric");
+  }else if(state == 1){
+    ClearScreen();
+    // Render informative text.
+    TextOut(0, LCD_LINE1, "LIVES:");
+    //NumOut(35, LCD_LINE1, player.lives);
+    params[0] = 35;
+    GraphicOutEx(0, LCD_LINE1 + 1, "ship.ric", params);
+    if(player.lives > 1){
+      params[0] = 44;
+      GraphicOutEx(0, LCD_LINE1 + 1, "ship.ric", params);
+      if(player.lives > 2){
+        params[0] = 53;
+        GraphicOutEx(0, LCD_LINE1 + 1, "ship.ric", params);
+      }
+    }
+    TextOut(0, LCD_LINE2, "SCORE:");
+    NumOut(35, LCD_LINE2, player.score);
+
+    // Render the player's sprite.
+    params[0] = player.x - 3;
+    GraphicOutEx(0, 0, "ship.ric", params);
+
+    // Render the player's bullets.
+    for(int i = 0; i < 3; i++){
+      if(p_bullets[i].alive){
+        RectOut(p_bullets[i].x, p_bullets[i].y, 0, 2, DRAW_PARAMS);
+      }
+    }
+
+    // Render the aliens.
+    for(int i = 0; i < ALIENS; i++){
+      if(aliens1[i].alive){
+        // First row.
+        params[0] = alien_frame;
+        params[1] = aliens1[i].x + alien_x_offset;
+        params[2] = aliens1[i].y;
+        GraphicOutEx(0, 0, "invader.ric", params);
+      }
+      if(aliens2[i].alive){
+        // Second row.
+        params[0] = alien_frame;
+        params[1] = aliens2[i].x + alien_x_offset;
+        params[2] = aliens2[i].y;
+        GraphicOutEx(0, 0, "invader.ric", params);
+      }
+    }
+
+    // Render the aliens's bullets.
+    for(int i = 0; i < ALIENS; i++){
+      if(a_bullets1[i].alive){
+        RectOut(a_bullets1[i].x, a_bullets1[i].y, 0, 2, DRAW_PARAMS);
+      }
+      if(a_bullets2[i].alive){
+        RectOut(a_bullets2[i].x, a_bullets2[i].y, 0, 2, DRAW_PARAMS);
+      }
+    }
+  }else{
+    // Render the hall of fame.
+    if(victory){
+      params[0] = player.score;
+      GraphicOutEx(0, 0, "victory.ric", params);
+    }else{
+      GraphicOut(0, 0, "defeat.ric");
+    }
+  }
+}
+
+/**
+ * The heart of the game.
+ */
+void game_loop(){
+  while(!done){
+    input();
+    update();
+    render();
+    Wait(50);
+  }
+}
+
+/**
+ * Initializes all game data and call the game loop.
+ */
+task main(){
+  // Initialize game data.
+  state = 0;
+  done = false;
+  alien_frame = 0;
+  alien_x_offset = 0;
+  alien_x_forward = true;
+
+  // Initialize the player and bullets.
+  player.x = X_MID;
+  player.lives = 3;
+  player.score = 0;
+
+  for(int i = 0; i < 3; i++){
+    p_bullets[i].x = 0;
+    p_bullets[i].y = 0;
+    p_bullets[i].alive = false;
+  }
+
+  // Initialize the aliens.
+  dead_aliens = 0;
+  for(int i = 0; i < ALIENS; i++){
+    // First row.
+    aliens1[i].x = BASE_ALIEN_X + (i * 14);
+    aliens1[i].y = BASE_ALIEN_Y;
+    aliens1[i].alive = true;
+    // Second row.
+    aliens2[i].x = BASE_ALIEN_X + (i * 14);
+    aliens2[i].y = BASE_ALIEN_Y - 10;
+    aliens2[i].alive = true;
+    // Alien bullets, first row.
+    a_bullets1[i].x = 0;
+    a_bullets1[i].y = 0;
+    a_bullets1[i].alive = false;
+    // Second row.
+    a_bullets2[i].x = 0;
+    a_bullets2[i].y = 0;
+    a_bullets2[i].alive = false;
+  }
+
+  // Initialize time variables.
+  then = CurrentTick();
+  then2 = CurrentTick();
+
+  // Start the game!
+  PlayTone(500, 1000);
+  game_loop();
+}
diff --git a/README.md b/README.md
index 116ed91..5e69df0 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,8 @@
 NXTInvaders
 ===========
 
-An Space Invaders clone for the Lego Mindstorms NXT
+A Space Invaders clone for the Lego Mindstorms NXT.
+
+This game is written in the NXC language. To compile on Windows use the BricxCC
+IDE avaliable at http://bricxcc.sourceforge.net/nbc/. On Linux systems install
+the NBC compiler available on the same page and run make.
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diff --git a/invader.ric b/invader.ric
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diff --git a/ship.ric b/ship.ric
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diff --git a/splash.ric b/splash.ric
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diff --git a/victory.ric b/victory.ric
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