Absolutely love this game and hope that there's a sequel coming. Big fan.
The first few levels are not really that hard, but you do need to carefully watch for your enemies' weaknesses and swap out towers accordingly to get a foothold.
I like the game overall quite a bit - great graphics and sound - but I feel like the balance could be better. It's fairly easy to get all the upgrades halfway through the game and then you're left to tackle the last few levels without any hope of an advantage. It makes the last level damn near impossible.
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