Zaz is an arcade action puzzle game where the objective is to get rid of all incoming balls by rearranging their order. Currently it includes 20 different levels and two modes of gameplay. The engine allows for easy custom level creation with unlimited number of paths, different speeds, ball-sizes, and rules. A 3D accelerator is needed for decent gameplay.
Arx Libertatis is a cross-platform, open source port of Arx Fatalis, a 2002 first-person role-playing game developed by Arkane Studios. Arx Fatalis features crafting, melee and ranged combat, and a unique casting system where the player draws runes in real time to effect the desired spell. The Arx Libertatis source code is based on the publicly released Arx Fatalis sources. This does however not include the game data, so you need to obtain a copy of the original Arx Fatalis or its demo.