One flaw: The random paths of the enemy makes it just as much a luck-based game as a strategic: in level 3, I died because the enemy would'nt move out of the room I where hiding, and capped me the second my invisibility was out. In level 11, I won on first try 'cause the greenie walk into the very rom I where hiding in.
I'd like to have a little AI on the enemy, so I could time and plan some, not just go on hunches.
There are some weird bugs with the towers's life: Sometimes when upgrading a tower, the life goes down. And too often i click repair, lose the money, and no repair occurs.
Naroghin: No selling units is not a flaw.
It's one of the things that makes this game difficult and gives it an egde ye don't find in other games. Ye actually have to play tactics and do planning, which makes this games so much better than other TD's.
What I would point out as a flaw, would be an upgrade to the cheesy graphic, which has been unchanged since Protector 1.
And people, let's not make Kongregate another youtube hatecomment site. People have a right to express meanings.
 "Toxie-Radd"){kind=icon}
 "Ultimate Assassin 2"){kind=icon}
 "Fancy Pants Adventure: World 2"){kind=icon}
 "Flash Super Tower Defense"){kind=icon}
 "Box10 Roaches TD"){kind=icon}
 "Stick Shot"){kind=icon}
 "Zombie Ramming"){kind=icon}
 "Texas Farm Thrasher"){kind=icon}
 "Desktop TD Pro"){kind=icon}
 "Ultimate Defense"){kind=icon}
 "Little Wheel"){kind=icon}
 "ROLY-POLY Cannon 2"){kind=icon}
 "Pirate Defense"){kind=icon}
 "Pyramid Tower Defense"){kind=icon}
 "Protector III"){kind=icon}