Same issue as Drachos, but it happened after Act 1-6.
I'd love a speed up button, if that isn't already implemented. As is, the game is very easy - it just takes a while. As a designer, I'd feel more free to increase difficulty if the playthrough for each level was shorter. Increased difficulty also means more of your animations on display.
This comment comes late into development, obviously, but I feel that mirroring the premise - playing as the monster girls, not the humans - would have allowed more eroticism to creep into the game. As is, winning perfectly = no sex. But if your towers are monster girls defending their homeland with sexy ninjutsu, winning perfectly = all the sex. Maybe it's not too late for this idea; you could keep the same board but have the player control the attacking monster girls. Could be a fun minigame, level, sidegame, whatever.
That aside, this was a relaxing experience. The sprite animations were the best part; the sheepgirl's especially is a special thing, the way she asserts dominance over the unit's cum-thrusts. I'd have continued playing just to see the others, if the bug hadn't happened. Neat stuff.