Yeah how do i do it?
You don’t, depending on which game you want it from. The Source engine has a tool called GCFScape and plugins and decompilers etc. to get models from Source engine games and only Source engine games. You can’t have any other game using GCFScape or the decompilers. There are, however, mod tools and other 3rd-party programs for some games. Grand Theft Auto IV has a tool called Spark IV to extract the models and textures. Crysis has some mod tools that allows you to export the models. Some games don’t have modding tools or extracting programs at all like Modern Warfare 2 or Metal Gear Solid 4 (I had a hard time thinking of 2 games that didn’t have them )
So it really depends on the game you want to “decompile” from, though Source is the only real game I’ve seen that requires you to decompile something. There’s no universal porting tool really.
Well i need to change the models animaions to a combine soldier can i do this?
changing animations is a bit hard, since you need to decompile it then.