Quite playable - would have helped to have a "fast forward" button - but the gameplay is very unbalanced. In particular UPGRADES are massively more powerful, and better value-for-money, than building a new tower. Most levels can be won with just one tower, upgraded as soon as the money comes in. Even the very final levels can be won with just two or three towers. Also, although the game introduces a wide variety of different towers and other defenses, most of them are pointless since the long-range tower introduced at the start of the game is better than them since its long range stops the inhibiting enemies from temporarily shutting your tower down. There isn't enough money, even in the final levels, to upgrade the really heavy-duty towers up to the same level you can upgrade one of the cheap long-range towers to, so you never really get to see the advantage of their special properties. It would help if the enemies were harder to kill, if there were more of them, if upgrades were either more expensive or less powerful, and there were different enemies that were more vulnerable to the special towers (since that would add variety to the game instead of just building upgraded long-range towers).