someone else mentioned it but a key you could hold (ctrl or shift maybe?) to be able to see health bars for each turret would be immensely useful. no other gripes besides that, and fun and addicting game.
i'd be lying if i said i wasn't disappointed about there being premium stuff, but this is one of the few exceptions where the content and quality are deserving.
enjoyed the game, two things:
1. it'd be really convenient if spells automatically charged so you didn't have to hurt your finger holding it down so much.
2. instead of making half the enemies immune to damage unless you reach a certain level, maybe make certain ones only damaged by certain spells?
the entire reason i play games on kongregate is because i don't want to spend any money, so i hate that you need to pay for half the game and not just for extra features like other games. that said it's very fun and addicting :)
@weirdguy i actually like the new spy attack a lot more because now if i need to kill someone i don't need to worry about wrecking an entire building and killing civilians now.
not nearly enough powerups to deal with the zombies. i find the puzzles more than enough of a challenge without running in circles from wolves while i figure them out. it would be nice if the enemies didn't know exactly where the mines you figure out were so i could at least lure them into it.
awesome game. all my minor complaints have been mentioned in other comments but among them are: a redo button, a number showing how many moves you have for an ace that level (instead of counting) and perhaps a hotkey for restarting a level. another thing i wouldn't mind seeing added in a sequel is possible moves maybe being highlighted so you can see all of your options.
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 "Shop Empire 2")
 "Bloons TD 5")
 "Endless War 5")
 "Snakes On A Cartesian Plane")
 "Sands of the Coliseum")
 "Enigmata: Stellar War")
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 "Paladog")
 "Fancy Pants Adventure: World 3")
 "Axon")
 "Memohuntress")
 "Arzea")
 "Defender's Quest (lengthy!) Demo")
 "City Siege 3: Jungle Siege")
 "Kingdom Rush")
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Yay Sakubo, yay!