Great game
But some constructive criticism, if I may:
1) The penguins can get stuck behind a wall. And it's extremely frustrating to have to wait till your zombie penguin dies naturally because he can't get to the last turtle. So maybe fix this so that after maybe 30 seconds or something, your penguin goes round?
2) I would like a button to end a level manually. This would also solve point 1 to some extent.
3) The game ended before I had any robo penguins :p. Maybe make custom levels or a survival mode?
4) Maybe allow for money gathering upgrades. Like increase the radius around the mouse where money is attracted to it. Because as you upgrade your penguins, you are in fact cutting down your own money gain! You can only collect money at a certain rate. Money also dissapears after a while. So if you have 5 strong penguins, you'll generate money faster than you can collect it. I held back on buying penguin number 4 and 5 a long time, and I'll tell you: the most lucrative thing in this entire game is getting 3 zombie penguins on level 30 (+ your activatable abilities). Any upgrades from there on, especially in amount of penguins, decreases how much gold you can gather.
5) Add hotkeys to the active abilities! Using them cuts your gold gain and makes bombs even more lacklusting than they already are
6) Change the bombs. They are quite lackluster. You have to go all the way to the bottom left corner of the screen with ur mouse, click a bomb and then click a location to detonate it with a very small blast radius! By this time, the bomb will no longer be useful if your penguins are strong and fast. Hotkeys would help with this, but maybe add blast radius increases to the bombs. The ONLY use I see now for bombs is when your last penguin gets stuck behind an obstacle trying to get to the last turtle. Which is a midgame problem. Bombs are entirely useless later in the game, and once you have 3 of them, upgrading to more bombs doesn't add anything to the game as using them means you miss out on gold anyway.
Conclusion:
Overall a good game, but I'd give it some tweaks;
