not bad. But if there are a lot of enemies in the view it gets very laggy and killing alot of fun. You should build in lod models or some kind of clipping.

And I am missing different weapons with splash damage and missions. And the enemies in the first level are very small and very difficult to hit with the standard weapon (espacially when its lagging like hell).

If you want to make such small items maybe put some bigger capsule next to them with which they crashed down on the planet. So I can find them better from far away and behind hills.