Subversive video game endings can be done right. The indie game Braid comes to mind — the ending of the game completely recontextualizes everything the player has done until that point. But the problem with Borderlands is that the ending isn’t just a subversion. It’s simply anticlimactic.
Throughout the game, the player is working toward a mysterious “vault.” This vault is rumored to contain incredible loot. And in a game about loot, that’s pretty alluring. But once the player actually gets to the vault, there’s nothing there but a big monster. The player has already fought big monsters — and this one just sits in one place.
While this was likely designed to create an aura of mystery and world-building around the concept of the vaults, it turned out to be a big disappointment to players. Even the developers admitted that they didn’t anticipate the negative reaction to the ending – but they did keep it in mind for future iterations.