I love tower defenses that is why I am so disappointed with this game. It's not a bad
game but it lacks some basic features of any good TD, e.g. the ability for the player to change strategy or to get empowered from failure; indeed in this game should you fail a level, you have no choice but to redo it with your current set of upgrades and spells. There is no mean to upgrade unless succeeding levels, no mean to respec... Should you have made unadvised upgrade choices you are stuck with playing again – or abandoning the game – without feeling better equipped neither more ready since the game mechanics lack depth and the right strategy is always straightforward.
Yet the gameplay is generally balanced, monsters are consistent with towers, towers do their jobs... But that's all. At the third (and last) upgrade level it's still just a stronger version of the basic tower; no additional ability, no new mechanics. Towers don't combo so don't expect more than legacy TD – which nowadays means shallow – gameplay, aside from the spells which are the only things that can occasionnaly be triggered in sequence to have a little more useful effect.
On the graphics side there are pros and cons: 3D modeling, animations, fog effect are good, but 2D graphics (used to illustrate the side story) suck, and the overall color choice/association is poor, leaving a dirty brownish atmosphere. The game terribly lacked art direction.
The side story (that serves as a theme, don't expect any meaningful connexion with the gameplay) is a drama about a little boy... again.
The camera does not zoom out enough to allow for all the field to be seen and since there are usually more than one generators and monsters are hidden by the fog, good luck for knowing from which generator came those monsters you just heard spawning... because, no, in this 3D game the sound is not even spatially localised...
Most one-man-made free Flash TD games allow for a better player experience & progression and deeper strategy, thus fun, than this game. There are many much better alternatives in free Flash games, and would you want to pay for a TD on Steam, go for real deals such as Kingdom Rush.
Edit: I played once more after my review, unlocked the last 3 towers, to find there were uninteresting. Bored, I uninstalled the game. At first I wouldn't have said that this game doesn't deserve to be on Steam but now I would; it is a very shallow TD, eventually bad.