Alan Wake - Building the Technology

Unreal Engine 3 free for independent devs

"However while it may be free to develop and release a non-commercial game, should you wish to profit from your hard work the current UDK license states that 25% of all revenue earnt beyond $5,000 will be paid to Epic as your licensing cost."

Unreal Engine 3 Free to Indies
Unity engine becomes free for independent devs

Unigine "Heaven" DirectX 11 benchmark

Unigine downloads

Unity engine becomes free for independent devs

"The Unity engine is becoming even more affordable to independent and hobbyist developers, as Unity Technologies has retired the $200 "Unity Indie" offering and replaced it with a free license, simply called Unity.

Developer Unity Technologies is keeping the full-fledged Unity Pro license priced at $1500. Alongside the new pricing shift, Unity is moving from version 2.5 to version 2.6, adding new graphics and pipeline capabilities. And Unity CEO David Helgason tells Gamasutra the company has Xbox 360 support in the works as well."

Unity Launches Free Option, Announces Xbox 360 Support