Awesome, but buggy
Wow, I just spent a whole day playing this game :D
While this was an improvement over the previous games in the series, I found that many bugs occured (Firefox 4, latest flash).
Every unit after modern-era machine-gunman produced some weird effects, some fixed after upgrading, some not. Those effects could range between mortar-man shooting inappropriate bullets that killed both my and their units, and enemies floating away due to machine gun fire (?!). Also, at some point, you simply cannot build more units if you have many spaceship, and the enemy stops building? And at the end, the final score does not appear.
But the bugs could be worked around by the fact that you DON'T NEED ANY of the units except:
-Hydra (upgraded)
-Bomber jet (upgraded or not)
-Spaceship (not upgraded)(if upgraded, just a couple, then spam the other 2)
With these, and at least the sniper rifle, you WILL win everything, by just spamming 1 kind and killing with your rifle, you'll never lose a life. If you have choice between the hydra and the jet, sometimes one is better than the other.
Rant: why the hell is the final upgrade to the best unit in the game to NOT be able to use that unit to win???? (spaceship just turns around when it arrives at the enemy base)