It's been almost a year since CD Projekt RED announced the development of REDkit, community development tools for The Witcher 2. Today, they've delivered. REDkit is now available, or at least it will be as soon as the servers are up and running. They were up for a minute, but now they're password protected. It'll be fixed... eventually. Hey, at least there's this sweet REDkit Beta trailer to watch!
REDkit gives aspiring developers all the tools they need to build their own settings, quests and complex combat systems using The Witcher 2's engine and assets as they will. The best part? It's free and available... err, will be available at the click of a button (link). For instance, you can put a dwarf on a bridge, and then set up a quest where Geralt knocks him off of said bridge, which completes the quest. This is going to be better than most games.
The Witcher 2: Assassins of Kings was released May 17, 2011 on PC, with the enhanced edition coming about a year later on April 17, 2012 also on Xbox 360 and PlayStation 3. Currently CD Projekt RED is had at work on at least two projects, The Witcher 3: Wild Hunt for release in 2014 and Cyberpunk 2077 for release in the far off future.
Update: The mod itself is still locked behind a password for the moment, though some people have confirmed that they are currently downloading REDkit. It's unclear if at this point CD Projekt didn't intend to release the mod, or they're just tuning their servers for the upcoming tidal wave.
I'm not sure of the exact size, but it appears to be at least 6GB big. A mod has also been released with a size of 912MB. In order to play mods, you don't have to download the whole REDkit, you only need the v 3.4 patch which is about 13.4MB.