Hmmm... u're right. Why can't it end differently? There's a lot of way to save the wasteland besides the purifier ???
I thought it didn't end if you had all the dlc, i thought you continued, im sure im still playing the game. I could be wrong, its been ages since i played it
You can beat the same file endlessly due to the fact that once you do the bit with the purifier, you don't get the option to save, and the game doesn't save.
Ah, never bothered with the DLC, as I didn't own the game when I played it. The ending was so crap though for people who didn't have the DLC. It seemed like the developers just wanted it to be over when they first made the game.