DotA burst forth from the Warcraft III mod scene with a mighty roar and a shower of blood, each drop growing into another independent MOBA, but tower defence games were a more creeping success. Oh sure, they'd been around before, but they bred madly in that weird environment then escaped into the wild. And, much like DotA, what's followed has never really strayed far from the original formula. 11 Bit Studios played with flipping it in Anomaly: Warzone Earth, controlling soldiers fighting through alien fortifications, but couldn't resist the lure of tower defence forever.
Its newly-announced Anomaly Defenders is a reverse-tower offence (or a reverse-reverse-tower defence) with the radical idea of building static defences to ward off advancing enemies.
Having been antagonist invaders in the first two games, the aliens are now the poor, put-upon invadee protagonists. Humans are coming, and they're a mite unhappy with what happened to their little homeworld. What does Anomaly Defender bring to the busy world of tower defence? Towers have active abilities so they do more than sit around, but bear in mind that Defense Grid showed that solid execution and a pleasant coat of polish can be enough. We may have squillions of TDs, but most of them are a bit naff.
Defender's due some time this spring. Here, have a gander at it in this announcement trailer: