You know it's good when one map lasts 3 hours...
I had a fucking BLAST playing this game, and I only played one map! At first, I was skeptical. It starts out rather slow, which is good for new players because it gives them some time to learn what all they can do first. It took 'til about level 35 for the game to really pick up and try to kick my ass. My first goal was to get the cash gun, to see what it did. And here's a tip. That gun is wonderful. At first it's almost useless because it's expensive to upgrade and you can't get it 'til later in the game, but after a few upgrades, that and the slow downs become your best friends! At the end of my session, my entire first floor was made up of fully upgraded cash guns and highly upgraded slow downs, which got me a ton of cash in no time.
All and all, the game could have benefited from a save function, for those that want to come back to levels they left off on and continue to fight, and more music could have helped too, but that didn't really take away from the fun factor I personally experienced. It's simple, yet complex, and the execution in this game is nearly flawless.
I give it a 10 out of 10, a 5 out of 5, and a spot on my favorites list.
Keep up the great fucking work, McGee. I look forward to the next project you have in the future.