it was a good game bit theres many things you could of added to it to make it better.
add some boss fights and more upgrades for more things, take out the helth regen and put in item packs you can pick up or make the npcs drop health packs.
make the weapons a little more powerfull because it just got lame shooting the same old guns for 30 seconds trying to kill one npc.
you could widen your array of npcs alost, make some that arnt robots and that have more diffrent then there size and shape.
also on a few levels i saw the npcs walking into walls and there i could not shoot them but they could still shoot at me. this game has alot of room for inprovement but it could be on the top 5 if you work on it enough