The game and all the code was completely written from scratch. Here are some things that are already implemented:

General:
1. Portal based game system, with 2D map
2. Customisable Input system, with config
3. Flexible and easy to use GUI system

Physics Engine:
1. Object-Wall and Object-Object collision detection
2. Different object physical properties

Graphical engine:
1. 3D Hardware acceleration with OpenGL through SDL
2. Support for older video cards
3. 24 bit PNG textures though DevIL(OpenIL)
4. 3D static and dynamic models are made from custom MD2 and KSM format

Sound engine:
1. SDL_Mixer is used for .wav and .ogg playback