Pretty good game. Needs to have a clearer idea on developing it's own tactics. I think you should double down on the idea of preparing each elevator for a purpose: one for little minions, one for big guys, etc. Have each level have varying waves, so we have to juggle our big guns to be constantly firing at the big guys, and our machine guns at the minions. As it is now, the strategy is basically "never upgrade, buy laser cannons, win."
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