Was playing as a dark elf monk - I fit all the shards into the chaos gate, it exploded, and I got a message saying I had finished the quest. However, I did not get the usual prompt to quit my adventuring life and get a high score entry (I did murder the wizened old man - not sure if this matters).

EDIT: Played through with another dark elf monk, didn't kill the old man, and the game properly ended - so killing the quest-giver is probably what messes it up.