It's a very fun tower defense game mixed up with some tactic and strategy. You defend multiple lanes which all have an indicator where the next threats come from. But you do not have enough resources to defend all lanes at once. Therefore you must adjust your tactics and shift your resources to the current threat. This can be challenging sometimes but levels are not too long and if you lose you have the urge to try it again with a different tactic. The difficulty may seem hard sometimes but as I mentioned before adjusting your tactics and earning a victory make it so much sweeter. On top of that the graphics, sound and overall presentation are very well done and you get a mysterious zombie sci-fi story (I am not at the end but it’s entertaining so far). What do you want more? ...Actually there is more if you are done with the campaign you can play endlessly in skirmish and even build your own levels.
