Like all the others in the Amnesia series, Amnesia: the Bunker has multiple endings. Unlike some of the others in the series though, the endings aren't too different from one another. There are technically only two endings with a sort of third. All of these endings basically turn out the same way, but players will most likely want to see all three of them before they feel their time with the game is complete. In order to see all three endings, players will need to pick up at the part of Amnesia where they have already blown up the front entrance.
Amnesia: the Bunker Ending 1 - Escape
In order to get this ending, players will need to just get out of the ruins. In order to do this, they need to evade the monster while moving some boxes to jump over the wall between them and freedom. How to do it can be seen in the video below.
Amnesia: the Bunker Ending 2 - Kill the Beast
The second ending involves getting rid of the monster; there is an Amnesia: the Bunker achievement called Beast Master for doing so. In order to get rid of the beast permanently, players will need to blow up one of the wooden bridges while the beast is on it, dropping it into the massive pits below. This video shows all the steps of how to get it and the ending itself.
Amnesia: the Bunker Ending 3 - Fall to Death
There is sort of a third ending to Amnesia: the Bunker. It's not much an ending, but it is worth seeing. If players fall from the bridges in the ruins scene at the very end of the game, a screen pops up saying that players should "Watch Your Step!" After a long fall, players see something red speeding toward them on the ground. This obviously kills the player, but it does seem like an odd thing to have put work into. Perhaps it gives the player and idea of what happens to the monster if they decide to kill it. Either way, here is a video of that "ending."
And that appears to be the only two endings players can get, with that third sort of half-ending. There's not much different between the two endings; they are both bad news for Henri either way. However, players will most likely want to see both endings before completing their time with Amnesia: the Bunker.
Amnesia: the Bunker is available for PC, PS4, Xbox One, and Xbox Series S/X.