Do you remember the last Sentinel game? Don't worry if you don't - even we had trouble recalling it straight away.
That's because Sentinel 3: Homeworld was launched some two years ago. That's two generations in iOS terms.
This is no dusty relic, though. In fact in its day we called it "the best of the tower defence genre with both depth and immediate action."
You might want to reacquaint yourself with this classic, because developer Origin8 has just announced that it's working on a sequel, Sentinel 4: Dark Star.
Origin8 isn't letting out many specific details on the new game, but it has dropped a few tantalising promises and hints over on a recent blog post.
Apparently Sentinel 4: Dark Star "hugely expands on its predecessors," although the developer promises that "the classic core Sentinel gameplay is intact."
That means plenty of sci-fi destruction involving "Commanders and Ship Weapons, destructibles and drones" - but with plenty of new toys to be revealed over the coming months.
Origin8 also promises that the core Sentinel 4 campaign will be vast - even bigger than Sentinel 3's (pictured below) - and will "take you to a distant, stricken world where the human-alien war takes a dramatic new twist."
Sentinel 3: Homeworld
There'll also be a new ancient alien race introduced with its attendant mysterious technology.
As for a release date, Origin8 is aiming for an early 2013 launch on iOS. An Android version will follow soon after.
Creators Paul Jackman and Laurence McDonald will be blogging about the development process from now on, so keep one eye on the Origin8 blog and one on PG for the choice cuts.
Since polishing off Kingdom Rush and Fieldrunners 2 we've been hankering for another high-class tower defence game. This could be the likeliest contender yet.