Epic Games has watched over 50,000 people download the Unreal Development Kit in just one week.
Released on 5th November, the UDK is a free version of Unreal Engine 3 that provides students and enthusiasts with tools that underpin some of today's best PC and console games.
Anyone can build and release a UDK-powered game for free, but Epic draws the line when companies decide to charge for their creations.
The excitable Mark Rein is "very excited" about all of this, and is "looking forward " to seeing what games and applications are made using the UDK.
Head over to the Unreal Developer Network to join a busy network of game-builders, and keep an eye on 3D Buzz for "dozens" of video tutorials for the UDK.