Sound effects and AI seemed solid. The only thing I'd say with the enemies is what Malek already said: that the enemies coming at the player constantly seems like a better fit. I think it depends on what you're going for with this one, though. The "Last Stand" feel seems to be aimed more at a wave survival kind of situation? I think for a game like that you need the enemies to be constantly going after the player. In a game that's focused more on exploration and survival it fits better to have enemies "patrolling" or even just chilling in a certain area that won't get aggressive until you get close, but I'm not sure if that's the case here.
As a player, I think it depends on where the game is going. I could see this as a rogue-like where you have to explore some western areas fighting skeletons, or as a wave survival game. Either way, I think more guns, some kind of power ups, some enemy variety, etc... is what you'd need if this game was going to be published.