Nice challenge, but leaves alot to be desired.
I did enjoy the difficulty of this TD. Something that isn't very common. I did find however that the restricted turret options, combined with the more prominent ground units, made turret choice pretty simple from the get go. Artillery is essentially all you need as you get your income rolling, adding in a few flak turrets as the air waves make their appearance. These two turrets, aside from maybe one Bunker in the first three levels, is all you need. On the last level you have enough income to go strong Artillery straight from the start.
Another problem I find is that the waves are identical on every map, and I sense no increase in difficulty from level to level, leaving the nature of your build mirrored as you play through, what worked on level one will work on every other level. Copy, paste, repeat, and so on.
My last gripe is that the flash does not save your progress when you exit out. Leaving you to repeat all the inital levels if you decide to take a break and close your browser.
All these things combined show there is alot that can be improved, but I like what this game offered and I'd love to see similar TDs in the future. Possibly with alot more flexibility and strategic choice.