OMORI

This ending can be achieved during the True Route and the Hikikomori Route.

During the True Route, don't check up on Basil. Leave his house, go back to your house (you can also grab a Steak Knife if you want to get a different version of the ending), and go to sleep. If you didn't pick up the knife, Sunny wakes up on Moving Day and he gets into the car. You can still see Something, implying Sunny will never get past his trauma. Sirens can also be heard, implying Basil killed himself. If you picked up the knife, Sunny kills himself with it while sleeping.

During the Hikikomori route, this is the only ending you can get. If you completed Black Space, Omori can choose to stab himself at any moment.