VatraLib
A simple cross-platform game engine for creating old-school 2D games
...The key idea is to provide the developer with low-level functionality - animation control, collision detection and the like - so they can focus on making games instead of re-inventing the wheel.
VatraLib has been rewritten from scratch, see current code under "Code".
The first installment of VatraLib used JOGL for graphics, JOAL for sound, and Spring for dynamic object creation. That (crummy) source code is available under "LegacyCode".