Now this is one I am excited about. The demo for TerraTech Legion was great fun, and I can't wait to build more vehicles in this bullet heaven survivor-like.
With the classic Tomb Raider 1 and Tomb Raider 2 fully playable with the open source re-implementation TRX, the team makes impressive progress with the third.
Luanti (formerly Minetest) is the popular free and open source voxel game engine powering some really fun experiences and a critical update is out now.