good game, nice visuals, the gameplay weas good, and the ''satisfaction''+the upgrade mechanics were good, but the game was too hard.
i mean, at some point, there were 20 flying beavers in the screen, and 15 in the ground, and i had to shoot all the bombs from the flying beavers, just to manage to shoot the ground beavers in time, and they were still arriving quickly at my dam attacking it, so until the next wave, i was a goner.
good game, but it needs to tone down the difficulty a bit.
(or to add more upgrades for the dam's hotpoints/damage resistance)