Orx: Data-Driven Game Engine
Tools and Z80 engine for creating adventure games. (RUST)
RPG dice roll simulator for vintage Tandy TRS-80 100/102/200 laptops
Multi-platform game engine similar to old Megaman with a stage editor
A generic 2D engine for any kind of game
A Simple Game Engine
Pig2D is a game engine for Java that uses a sprite-based interface.
Reference implementation for the Doom game engine.