1. 2 Gun Towers to start.
2. 1 Splash Tower one square off from any inside corner.
3. 1 Air Tower. Don't worry if it takes all day to kill the Air Creeps. They'll be the only thing on your map and you can still Send Next Wave while they're out.
4. 1 Slow Tower in the same inside corner.
5. 2 Splash Towers around the Slow Tower in the inside corner.
6. Repeat in the 4 remaining inside corners before upgrading.
7. Win. Put your upgrade points in Splash/Slow Towers.
Pause button? Upgrade/Build costs need some tweaking with respect to damage/range/rof gained. Often better to build more towers than upgrade. Otherwise really nice twist on tower defense. Not as good looking as some other TD games of late (aHEM, bubble...), but cute graphics don't amount to a good TD game. Good job. 4/5
Ditto what Rockbass said. The same "strategy" will get you through each level. You sit back and wait for your units to build (while the AI's units just magically appear) then march forward. The End.
Lvl 18 can go to hell. The YouTube solutions don't work in the most recent version. Great idea for a game, but I'm gonna take out my frustration on your rating. 3/5.
Hallmark of a great game: when you finally look up the walkthrough to get you through a level, you find that you rejected the 'correct' solution half an hour ago because surely no one would create a puzzle with a solution whose timing is so damn tight. 2/5
I think I have to drop my previous rating by an additional star. Progress in this game isn't made by skill, but by waiting for all the random elements to align themselves. Success in each level has come easily when this happens. 3/5 for concept.
Difficulty is good. But could the guards walk a slightly more predictable or HUMAN path? I'm watching the guy just stare into a corner right now. But I'll likely be caught if I run past him because he could turn 90 degrees at a moments notice. Some way to stun guards would be good. Perhaps at the cost of a noise that attracts other guards or drains a lot of energy? 4/5