The Anomaly games gained attention not only because they are staggeringly gorgeous, but because the gameplay was a clever twist on the age-old tower defense genre. Past games had you playing as the creeps fighting through the towers, but Anomaly Defenders is more traditional—you're in control of the towers, but it's the humans you're fighting, not aliens.
This is the final installment in the Anomaly series, and the humans are close to wiping out the alien menace. Not just on Earth, but everywhere. Have they maybe gone a little overboard with this whole genocide thing? We humans do tend to do that sometimes. Your character has been recruited by the aliens to hold off the human invaders just long enough for them to reach their escape pods and leave this corner of the galaxy behind. To do so you get access to all the devious defense towers you have been battling against for the last few games.
This isn't just a run-of-the-mill TD game, though. Anomaly Defenders includes resource management, a full tech tree, and some cool strategic planning like rerouting the enemy troops to spring traps. Of course, the game is still visually amazing. You're looking at $3.99 to pick up Anomaly Defenders, which is $1 less than Anomaly 2. Seems like a good deal.