Unreal Tournament dev video gives you a look at Capture the Flag level Titan Pass
Epic Games has released a developer diary giving you a look at the making of Unreal Tournament's Capture the Flag level, Titan Pass.
In the video, the artists, developer and designers show how a "rough sketch for CTF-Outside" becomes a fully-realized, playable level.
Unreal Tournament is currently in pre-alpha, the most recent update occurring in October with the Halloween event, and you can try it out for yourself by downloading it through the official website.
Epic announced development of Unreal Tournament in August 2014.