I know this is a very specific question, but does anyone know anything like this?
What I mean by "like TAB" is that it's an RTS and/or citybuilder where you're constantly under attack from all sides, and taking + holding more of the map is the primary thing that enables you to progress in the game.
Age of Darkness is really fun and I know another update is in the works but I've already played it to death much like TAB. Alien marauder just felt like off-brand TAB and I got bored of it after beating each map once.
Kind of an old one, but Creeper World is kind of like that. I don't know if it's actually released, though. It was originally a flash game and the developer was making a new version, but in the devlogs I've seen he had changed the game significantly multiple times and then I lost interest. Might be worth checking out either way.
There’s been a bunch of Creeper Worlds, they’re all fantastic! 3 was my favorite, though 4 was a solid entry (and is 3D!)
I've actually played that one a lot lol, I've played the original flash and there's a newer version on Steam.