Well, it's alright.
-animations are fine
-sounds get a little irritting
-more weapons would have been nice (mines, flamethrower, gatling gun). Different slot for each weapon, Q and E to cycle between them
-change the single shot to a sniper that does more damage
-add more upgrades and things you can "buy" with energy - a faster recharge rate upgrade would have been awesome
Tip: different weapons seem to be more effective against different enemies. Oh, and use a grenade as soon as it's charged. They help... a lot.