So UFOs are flat, but with a hole inside!

It’s not split screen, but an enjoyable game for two players in the same screen (so couch coop):

https://en.m.wikipedia.org/wiki/Spiritfarer

You play the new “Reaper” and his cat. Collect lost souls, that still have some issues to solve, travel the “in between” spirit world, build a house boat, take care of gardens, make music, etc. The artwork is cute, while the topics of the lost spirits can be unexpected sad. Still a great game to relax!