This is not a traditional tower defense game. You don't build mazes. You don't upgrade towers. There are no units to attack. Yet, it contains a lot of the same mechanics as TD games: you build towers which attack for you; you decide whether to spend or invest resources; you strategically place towers at the right places and times. Thus, I don't feel uncomfortable categorizing this in the Tower Defense genre.
The game goes like this: you expand your base to earn resources. The larger the surface-area of your base, the more resources-per-second you earn. Meanwhile, the "enemy" is simply a geyser of fluid (called "creeper")
which spreads out in all directions. If the fluid touches a tower, that tower dies. You use your towers to push back the fluid, so you can get close enough to destroy the geyser(s).
On paper, it sounds stupid. But then again, I would have said the same thing about TD games at first, and now they are my favorite genre.
In reality, this is a fantastic
game. The game constantly introduces new gameplay-elements throughout the campaign, keeping it fresh and unrepetitive. The levels are never too easy, but also never too hard (the main campaign, at least)
. And after beating the campaign, the game opens up hundreds of levels created by the developer, his friends, beta testers, etc. giving this game immense replayability.
I've played a lot
of TD games, and this is one of my top 3 TD games of all time (just behind Pathery and Entropy TD)
. If you enjoy TD games, I personally guarantee you will enjoy this game. 10/10