CryEngine

[Hotshot]

This is even cheaper than Unreal Engine and Unity 4!

CryEngine 10$ monthly Royalty free !!!
Unreal 4   19$ monthly
Unity 4     75$ monthly

http://www.gameinformer.com/b/news/archive/2014/03/19/crytek-announces-royalty-free-cryengine-licensing-subscription-plan.aspx

http://www.cryengine.com/news/crytek-announces-its-cryengine-as-a-service-program

[rdc]

The Torque engine is open source: http://www.garagegames.com/products/torque-3d
There is also a Torque 2D engine as well: http://www.garagegames.com/products/torque-2d

[Hotshot]

there is CryEngine tutorials on how you make in 5 mins!

http://docs.cryengine.com/display/SDKDOC2/Tutorial+-+My+First+Map