They have a large publisher (Paradox Interactive) who prescribes their schedules. They also made bet bookings from Cities: Skylines that put them quite evidently in AAA. Finally, they release the games for all major platforms. All together, this describes a AAA game developer.

In contrast, an AA developer would work with publishers like Annapurna Interactive, Devolver Digital or Team 17, while a III game would have a much smaller scope - like The Witness, The Stanley Parable, or Hellblade: Senua’s Sacrifice. It is clear that Colossal Order doesn’t work with a small publisher or make games of indie scope.

If you were just sealioning, don’t do that please.