An easy thing to pick up (not sure if it is for a *complete* beginner, though...) might be Game Maker. I can't tell you anything about it really though, because I haven't used it since version 4. You might not create anything truly groundbreaking with it (it's 2D not 3D although people have hacked together Doom-ish 3D games with it), but I have seen some definitely cool stuff with it. You can go as complex as you want. You don't need to program, but you can if you want (and if you do it will be much better
). It has support for a range of things, including multiplayer.