Highly evolved engine based on id Software technology, available under dual license (GPL, proprietary licensing for commercial use available).
Hipnotic quake-c (original release 3.12.97) - with compiler warnings fixed. A great mod code base if you want: rotating brushes / doors, water swell, rubble, clocks, earthquakes, etc. Featured in "Scourge of Armagon" - Mission Pack 1. NOTE: any code that requires models / sounds must be modified or you must acquire the mission pack.
Does anybody know where the .fgd for SoA is?