you guys realize that eventually u will have to code c# or a scripting language to get translated.. valve's source engine has a full SDK tho it is based on open gl and it dose need a-lot of shader work.. so you must know shader language and native opengl like the back of your hand and lets not talk about the GUI system cus thats a real major kick in the ass. Wish you luck
tho..
PS: Take a look at this:
same as valves opengl tehnology.. comes with a SDK also. And its written in java, tho still native opengl is used (like valeve's) and you will never need to mess with it, also it's pixel shader system is the latest shader tech for openGL. And unlike source engine it has a procedural terrain.
Also whats an anime game with out a cartoon post shader? xD
Their source engine is free i think, also the engine is not like HL, HL is their game achieved with source engine. And also if their game is not for commercial use and they dont sell the game, then the engine license remains as a share ware game(Since openGL is open-source) and they are allowed to do anything as long theirs no profit coming off it.