GeoBox is a game engine for the indie game Cave Story. It's also used in Them's Fightin' Herds for pixellobbies and Story Mode overworld maps
It promised the following features (according to the thread):
- Live world editing (aka, in game world editing)
- Full script system in Lua (class creation, level scripting, inheritance from C++ classes)
- Script can be recompiled while the game is running to enable rapid prototyping and parameter testing
- Overwrite protection for files (engine backs up any file it recycles)
- Performance diagnostics tools
- Full Lua IDE with autocomplete enabled
- Runtime lua debugging tools
- NavGraphs for NPC AI
- Object Oriented lua programming
- Physics engine powered by Chipmunk2D
- Subsystems such as physics and lighting take advantage of multicore systems
- UPD and TCP networking are functional (but still in the works)
on the Cave Story Tribute Site Forums a user named Fluffball joined the forums on Aug 11, 2014 and created a thread on Feb 20, 2015 called Geobox Engine getting ready for public use in which Fluff was talking about a game engine called GeoBox he was working on. After some edits he posted a link to the Documentation of GeoBox (dead link but can access with Wayback Machine). On Jun 10, 2015 at 3:57 AM he posted in the thread that he has shared the code with some people for private testing. It was also his last message in that thread. Last message in that thread in general was on Nov 30, 2015 at 3:00 AM. According to his forum profile he was last seen on Dec 23, 2015