Replica Island
A side scrolling video game for Android.

Authors: Chris Pruett and Genki Mine

This code and artwork is released under the Apache 2.0 license.  See COPYING for details.


Replica Island is a side-scrolling platformer for Android devices.  It stars the Android robot as its protagonist as he embarks on a dangerous mission to find a mysterious power source.  This is a complete game: all art, dialog, level layouts, and other data are included along with the code.


The code is structured into several Activities for the main menu, level select screen, dialog window, and main game.  Most of the code in this project is related to src/com/replicaisland/AndouKun.java, which implements the core game Activity ("AndouKun" was the code name for this project and you can find references to it all over the code).

The game loop itself is structured as follows:

AndouKun.java spins up the game, handles input events, deals with pausing and resuming, and also manages the progression across game levels.

Game.java is a layer of abstraction between AndouKun.java and the game loop itself.  This class bootstraps the game, passes events through, and manages the game thread.

GameThread.java is the actual game loop.  It's main utility is to manage the main loop (MainLoop.java), which implements the rest of the game logic.

MainLoop.java is the head of the game graph that describes the Replica Island runtime.  Anything managed by MainLoop will be polled once per frame, and children of MainLoop may themselves have children which will be polled.  GameObjects are a specific type of game graph node that only contain GameComponents as children.  GameComponents implement individual features (collision detection, animation, rendering, etc) of individual game entities.  GameObjects are generally parented to GameObjectManager, which activates and deactivates its children based on their proximity to the camera.  GameObjectManager is a child of MainLoop.

The last step in the GameThread is the rendering step.  Rendering does not occur in the game thread.  Instead, render commands are queued up by the game thread and then handed to a separate render thread at a synchronization point.  The render thread is mostly implemented in GameRenderer.java, which is run by GLSurfaceView.java.


Here are some interesting files in this project.

res/raw/collision.bin: This is the raw collision data.  Line segments and normals.

tools/ExtractPoints.js: This is a (rather horrible) Javascript tool for Photoshop.  It will walk closed paths and produce a text layer describing them as line segments and normals, organized by tile.  It takes a long time to run and is probably the worst code in the entire project.  res/raw/collision.bin is the binary version of output from this tool.

res/xml/leveltree.xml: This file describes the non-linear level progression through the game.  It is a tree, each node of which may contain one or more levels.  Continuing to the next node requires that all levels are completed.

src/com/replica/replicaisland/BaseObject.java and ObjectManager.java: These are the core nodes of the game graph.


Chris Pruett wrote code, dialog, made sounds, and defined the core game design.
Genki Mine made all of the art, most of the levels layouts, all of the character designs, most of the sound, and also contributed to the game design.
Tom Moss got the project up and running and then sat back and let us make it cool.

Special thanks to Jason Chen for awesome rah-rah cheerleading support, Casey Richardson for excellent play testing and design feedback, Tim Mansfield for dialog edits, all 1300 users who participated in beta testing, and to the Android team for continued support.