I keep falling into the trap of thinking I've seen all the world's games and there's nothing new left for me to discover. This is because I am very arrogant, but then I stumble across something like Creeper World 3: Arc Eternal. It's a strategy game in which you battle a gradually encroaching goo as it flows around and across terrain. It's the third in a series of 2D, indie strategy games. It has a story campaign, a level editor, terraforming, and enough unit complexity to evoke Supreme Commander. It has a demo. It is now on Steam.
Let this goo slowly start to colonize your brain by watching the trailer below.
It's got base building and unit management, but Creeper World also shares much in common with tower defense games. You're not fighting a collection of different units controlled by a player-aping AI, but instead struggling against "a fluid-like substance spreads over the terraformable terrain."
Like Infested Planet, it looks like part of the fun of this is that you're never not firing at an enemy. It's a constant assault, and the simple, slightly ugly sprite graphics cease to be a distraction when the screen is swelling with activity.
The game came out last October, though it seems we missed it at the time despite Kieron and Quinns taking to the previous games. Now that it's on Steam, and I discover that it exists, I might join them. It's $15/£9 when bought directly from the developer, or .