The current beta version can be played here www.distantmelody.net/desent. Let me know what you think! Use WSAD to move, aim with the mouse and use left mouse to shoot. Use R to reload and ESC to exit the game. There are currently 24 levels.
You will notice 4 player characters even though you only control 1. The game will eventually become 4 player co-up multiplayer. Of course a single player mode will still be available.