"A fantasy d20-themed dungeon crawler", to quote DarkGod's comment. Inspired by Incursion by Julian Mensch. Made available under Open Game License. This is a non-profit fan project. No money is made. There are currently only two people working on the mod. However, we have released several beta versions so far.
How two busy code-monkeys created this mod :)
Busy bees, or rather hornets maybe (big coding stings it appears)?
Seeing this development history is quite alluring.