At the last Winter War, I had a great time playing the rules-lite RPG Lady Blackbird. The mechanics are self-contained and easily adaptable to all kinds of scenarios. The RPG style is more story-based, more "fluff" than "crunch," than D&D or even Savage Worlds, and makes for a very fast, improv-style game.
Anyway, I was inspired to write up a scenario using the old TSR Star Frontiers RPG setting. I left off the page with the gamemaster notes, so don't worry about spoilers here.