Alright so this game is some kind of fighting games. The stage are like a sandbox, and you can dig a square of it by I don't know how. And I can only remember this 2 playable character. One with 2 big arms and walk with both arms, another one is alien. Also there's a cut-scene of 2 aliens, 1 of them is holding guns, pointing it to the other one, and then the other one rotate the gun this alien is holding, pointing to itself.. and then it shows that the gun actually fire from the back of the gun, which mean that the alien is actually tried to suicide. Sorry for this but I can't remember anything other than that, this game is 3D IIRC.
The only game that your description reminds me of is Bio F.R.E.A.K.S : http://en.wikipedia.org/wiki/Bio_F.R.E.A.K.S. Just a guess bro...
