You have all put a lot of effort into making some excellent recommendations. Which, unfortunately, I’m going to ignore.
I actually have Toon, but it seems too silly for my current mood. I’ve played GURPS with this gang, and nobody likes the combat system. Also, too complex for a one-shot, really. Which is the same problem I’ve got with most systems for this sort of thing; too many rules to absorb to make one-shots worthwhile.
So, I went and found Risus. It’s a six-page set of rules. PDF format. It’s actually pretty neat, and has some nifty ideas that I think would be worth trying out.
So, to the plot. I came up with this in the past few hours; it’s based loosely on a dream I had several years ago.
The players are roomates in a house in a college town, probably Tucson. They’re awakened one night by an odd series of noises from the living room; they’re confronted by a small, humanoid-looking alien-like glow-in-the-dark guy. He fights them, and then escapes. Into the dryer. The interior of which is glowing green.
If they don’t follow him, more will come through. If they do follow him, they’ll find themselves in an alien world, a strange place inhabited by at least two races, the unfriendlies (like our glow-in-the-dark pal) and the friendlies (who are so far, from what I can tell, kind of leprechaun-like). The PCs will start off by getting away from the unfriendlies, who have the gate on their side surrounded.
During that combat, they’ll find that they have each acquired a randomly-selected magical ability.
When they reach the friendlies, or the friendlies find them, they’ll get the explanation for the events. It seems a few days ago, a magical artifact appeared in their world, at the location the gate is at now. It came from the player’s world, and as long as it stays in this alternate dimension, the portal will remain open, and will grow, and the unfriendlies will invade the Earth.
The object that came through and started the dimensional rift? A sock.
I think I’ll call it SockQuest.
