Fun game, last level is the only challenge. I beat the entire game only using mini-guns and shotguns. The bazookas are a waste of money and snipers are only useful against the invisible ones. Endless mode is more for wasting time than any actual challenge. I walked away and let it play by itself without issue. The walls are pointless to buy since they provide very weak protection. Overall it's a fun game to waste time on, but not much else. Maybe if you do a sequel try for more of a challenge. Artwork is awesome and the game plays smoothly. I didn't run into any issues.