What's a good Android game for someone who likes tower defense but wants something with a bit more...oomph?

Okay, so Galaxy Defense: Fortress TD, right? From a technical standpoint, the graphics are pretty polished, runs smooth as butter on my Pixel 7, barely uses 50MB of RAM. But more importantly, it's got some depth to it. The dev team really thought about the upgrade system, so you're not just mindlessly leveling up towers. You're making actual strategic choices that impact the game. The different enemy types keep you on your toes, and the maps are well-designed. No spaghetti code situations here, thankfully! Plus, the sound design is surprisingly good; it really adds to the atmosphere. I've sunk a good few hours into it already, and I'm not usually a huge tower defense guy. It's a solid choice if you're looking for something that's easy to pick up but hard to master. The API integration for ads isn't too intrusive either, which is always a plus.