One neat engine I came across is Angel-Engine. Info from the project site:
- Cross-Platform functionality (Windows and Mac)
- Actors (game objects with color, shape, responses, attributes,
etc.)
- Texturing with Transparency
- "Animations" (texture swapping at defined intervals)
- Rigid-Body Physics
- A clever programmer can do soft-body physics with it
- Sound
- Text Rendering with multiple fonts
- Particle Systems
- Some basic AI (state machine and pathfinding)
- Config File Processing
- Logging
- Input from a mouse, keyboard, or Xbox 360 controller
- Binding inputs from a config file
- Python Scripting
Some users (including me) have succesfully (without any major problems) compiled it under linux.