Make a hostile leviathan in the future that migrates around the map, maybe make it the weakest damaging of the leviathans but still powerful. Theres a migratory leviathan thats docile but still very cool, but it’d be interesting if there was one that migrated around the whole map, slower then the other migratory leviathan, that would force you to occasionally leave your home base, as it would suddenly become unsafe to be there, potentially even inside of the base itself, with the leviathan maybe being able to disable the power of bases nearby it.