GURPS Post-Apocalyptic homebrew. One hero finds a multi-warhead rocket launcher, along with a cache of assorted warheads, including one mini-nuke. I can't remember the damage for the weapon, but I'm pretty sure it was somewhere between 60-100d6 in a several mile radius; in GURPS, you get your Health score in HP, so an average hero might have 10 HP and a really tough one MIGHT have 14 or 15 HP. He loads the launcher up to full capacity, all excited that we have an actual nuke, "just in case".
We play through a couple of days' worth of game time. We come upon a small city, mostly intact. We decide to get greedy, break into a military installation, and try and steal some swag to use for barter. Naturally, we get caught, and after a short chase we are forced to barricade ourselves into an office building, still fairly populated. We fight from floor to floor, fending off troops in Power Armor (personal mecha). We are pretty liberal with our rocket payload, and we're definitely fighting a losing battle.
THEN, we get near the top of the building, and a heavily-armored atttack helicopter finds us and starts spraying the entire floor with machine-gun fire. In a fit of panic, our hero says "F*** it! I unload the rest of my missiles on the helicopter!"
Guess we ALL forgot about the nuke... GM included.
WHUMPF.