As Lilith's Slave said, it only affects your score, unless you make so many visits that your characters ages start to affect their stats.You can continue killing monsters after you've completed the game. I think Dragonsand and New Sorpigal respawn every 6 months, Bootleg Bay after a year, and everything's respawned after 2 years, including all the dungeons. One of the players - Klar - continued to kill monsters to the point at which his party was up to level 400+, IIRC. So it's actually handy to nuke a town, go to prison for a year, then clear Dragonsand, New Sorpigal, and Bootleg Bay, go to prison for another year, and clear the whole map again. There are no quests, obviously, so you can't get a saintly reputation any more, but becoming notorious is no problem. The Training Ground in Paradise Vally will continue to promote you indefinitely, so far as we know.
If that's the sort of thing that you want to do, of course . . .
