Deep Dreams has a total of 3 different endings, all of them with their respective requeriments to trigger them. All the game's endings are listed below.
Unlike most YNFGs, there's no need of dropping your alters in any specific place since there is no way of getting rid of them, but getting all of them is still mandatory.
Ending 1
Requirements: Get all 12 Alters.
Description: Once you get every Alter, wake up and open the door Mariana refused to go through, now you'll be able to leave. Once outside the room, go to the rightmost door (The other ones won't open) and open it. Mariana will finally be outside of her house, leave through the only way.