[GB] Retr0 GB: my Game Boy engine based on GBDK

What is Retr0 GB

I worked on a Game Boy game engine for a month on my free time to be prepared for the Global Game Jam 2018.
Retr0 GB was developed in C using GBDK.

Features

• Code your game in C
• Manage sprites and/or box collision separately but in the same structure thanks to Movables (all non-static element as sprites, collision or both)
• Let your movables move freely pixel by pixel or constrain them on tiles (like RPG games) and let them interpolating their position themselves to next tile
• A complete collision system
• Movable vs Movable blocking collision
• Movable vs Movable overlap with automatic callback calls to manage easily what to do when movable A overlap movable B
• Movable vs Map
• Collision layers and layer masks to define which movable can collide with which other movable
• Sprite animations
• Animated tiles (animation for map background)
• Map loader to load map easily
• Calls to custom callbacks on map loaded and on update (called every frame) for each map
• Easy to use map scrolling, define which movable can scroll with the map and which movable can ask scrolling from its own movement
• Basic dialog system
• Music player (gbt-player implementation)
• Custom types as math 2D vectors or box
• Helper modules as functions to convert a screen position to tile position

Retr0 GB is now on Bitbucket, the engine is still in work in progress, so feel free to fork it as you wish.