Open Source Game Clones
Not quite ready to submit this to the list yet, but I've been working on a Quake 3 engine clone from scratch in C# with Bridge.NET, targeting the browser and WebGL.  It's been a super fun project so far -- a few days of part-time work and I have levels rendering nearly perfectly and I'm making progress on character model rendering.  Repo is at https://github.com/daeken/WebArena and you can see a live version at http://demoseen.com/bridge/Still a ton to do, but I'm really digging it.Edit to add: WASD + Space/Shift + arrows to control the camera.