Some of the puzzles were a little arcane... possibly too much so. I managed to figure out about 90% of this game myself... including the symbols for opening and closing the two tubes near the end, but Energy and Gravity and On and Off totally eluded me, and I had to refer to the walkthrough. I've given this 5/5 for sheer enjoyability... but a few more clues around some of the symbols would have made this even better.
Firstly, Great Stuff.
Secondly:
1. You need to rebalance tower damage vs cost. eg:Those $500 towers are maybe a touch overpowered, or too cheap. I stacked those on the 6th level, and nothing even made the first intersection. The lightning tower ($750) doesn't seem to do much at all.
2. The ability to sell towers would be great.
3. A click to complete the score count-ups on the Mission Complete pages would be great. They can take a while.
4. Splash damage towers, maybe?
5. Vehicles as well as walking troops could be cool.
6. Mute music button, or more music options/variability.
Other than that, I really enjoyed it.
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