I simply love the rhythms you made for this, especially the rhythm you made at 0:58, that melody blends greatly into looping. The bass back it up great as well.
I'm sorry, but I'm gonna agree with the guys under me as well, a better percussion could be needed.
But I actually got a solution for it:
Instead of setting the snare on even beats, and hats on offbeats, then swag them around. I'm sure that would give a more battle'ish feel.
Else I suggest searching for some 8-bit percussion, and still try to keep the "4 instruments only" rule.
I'm loving this, I'm looking greatly up to your project!