After hearing about this on a mailing list, I thought that it was a really good idea to pass it along to as many people as possible. If you haven't checked out one of Marcus Rowland's RPGs already, you really should and because of the charity element this is a really good place to start.
I did see an early version of Marcus' Flatland game and it was really intriguing. The guy comes up with some really cool concepts.
The Flatland Page
Imagine a world of two dimensions and plane geometry, in which the very idea of height is considered insanity and the darkest heresy. Where the only thing that matters is the straightness of your sides and the regularity of your angles. Where the slightest deviation from the norm can lead to arrest, imprisonment, execution (and consumption by your peers) or a lingering death by starvation.
Welcome to Flatland. Enjoy your stay…
Action and adventure in a world where characters are supposed to be two-dimensional!
Whether your adventures take you to the criminal classes of The State and an encounter with legendary gang leader “Scarside” Al Gebra, across the border to Polygonia and an attempt to rescue Mad King Euclid, or into the glamorous world of politics and diplomacy with the multi-faceted polygons of the aristocracy, there’s something here for you. Best of all, by buying this game you’re supporting charity: All of the author’s income from this game will be donated to Médecins Sans Frontières (Doctors Without Borders)!
The Original Flatland Role Playing Game expands material originally published as part of the Forgotten Futures CD-ROM, completely rewritten and updated. It includes the novel, complete rules for the setting, three adventures and four adventure outlines, a complete wargame by Matthew Hartley (Tusk, Aeronef, etc.), full-colour cut out character figures, extensive background material, and much more.
You can buy a copy of the Flatland RPG PDF here.