If you try for the legendary route, be careful not to pick up the sponge before it changes colour. There's no way to reset if you make that mistake, so you have to reload the page and start right back at the beginning. For that frustration alone, 1/5.
Why is this tagged idle? I just came back to it about 12 hours since I last played, and I had made no progress in that time. It's not an idle game if you have to leave the game running and your computer on.
The tutorial mode is allegedly on, but after the cut-scene ends I'm left looking at a screen with no hints, and although I think I've tried clicking everything the only things I can do are bring up menus. What are my goals? Where are my characters? What actions are available?
Simple and fun.
A couple of things could be improved though, and are worth taking into account for your next game. Controls: when the game is played solely with the keyboard, it's frustrating to have to switch to the mouse to restart. Instructions: I'm still not sure what difference blue dot frenzy makes (I'm guessing that it affects the score) or what "Gold Mode" is. Feedback: I don't think I get any feedback on how close I'm getting to eating 20 dots and activating "Gold Mode". But the feedback when unlocking a character or collecting a key is so intrusive (and slows the game down so much) that it has killed me more than once.
On the fourth level it's refusing to advance to the second wave, even though I haven't seen a live enemy for a couple of minutes. Hitting a bug which forces me to restart before the game has really got anyway => 1/5.
Most games of this genre have a final level which is a few orders of magnitude harder than everything which went before. This one curved much more smoothly: there were some levels where I had to think, but none which felt unfair, and the final level had a bit of complexity but didn't require pinpoint precision. Thumbs up.
I can't understand why putting spikes in the pit should prevent me from getting the Governor achievement. That's much more frustrating than the usual point-and-click issue of the obvious being disregarded in favour of the obscure (e.g. requiring me to find a length of hose rather than being able to take the axe to the pump and acquire some hose from that).
The fractal maze idea is fun, but the end boss lets the game down. The only reason I didn't give up running around and shooting it is that convention dictates that that's what you do with an end boss - but the same convention also dictates that there should be a power bar or progress meter showing how close it is to dying.