My writings are divided into two parts. To wit:
I'm making a distinction here. I have, for example, designed several games using Icehouse pieces. I consider these to be games I've designed rather than articles because they are complete games, whose rules do not rely on anyone else's rule set. All of the games I've designed require you to provide some kind of equipment to play; some just require a slightly more specialized type of equipment. On the other hand, the articles are all for someone else's games, and depend on knowledge and/or ownership of a copy of a ruleset.
That said...
Cars, the game! Remember being a kid, having a whole pile of Hot Wheels or Matchbox cars, and "playing cars" with them? We sure did that. There were always discussions about whose car was more cool, about who were the good guys and who were the bad guys, and for some reason all of our cars could fly and shoot. I give you all of that (even the "I got you!" "Did not!" "Did too!" arguments, though these are more ritual than anything). All you need are some of the aforementioned cars, a couple of 10-sided dice, and a place to play. For two or more players.
The Open Source Paper Roleplaying Engine Y, also known as Osprey. This is a freely distributable roleplaying engine. Consider it to be unfinished but barely usable with a goodly amount of tweaking. Points and skills based. You'll need paper, polyhedral dice, and all of the other trappings that usually go with roleplaying games (such as chips and soda pop). For as many players as you'd play any roleplaying game with (two or more).
Martian Tic-Tac-Toe. This is tic-tac-toe as it might have been played thousands of years ago on Mars. Requires Icehouse pieces or a Black Ice set, or just nine pieces of each color, divided into three each of three separate sizes or distinct markings, and a tic-tac-toe grid big enough to hold them. For two players (theoretically for more).
Ice Castles. My second attempt at designing an Icehouse game. I'm not really happy with it; it looks like there's a cool game in there somewhere but I think it's something I put out there just to have designed a second Icehouse game. If someone else wants to take it over, feel free. For two or more players.
Bottoms Up. My third Icehouse game. I haven't playtested it yet but it looks like fun. Make stacks of Icehouse pieces with the caveat that whenever you make a stack, things happen. Requires a set of Icehouse pieces and a Black Ice set. For four to six players.
Bath. The first game I've ever designed to be played with an ordinary deck of 52 playing cards. Make plays onto a central pile. The last player to be able to play scores points. For four players.
The Great Martian Ice
Machine, my fourth Icehouse game. This one has been
tested, though not extensively, and includes some extra comments at the end.
A conversion article for Robot Warriors to 4th edition Hero System. This was published in Hero Games' Digital Hero zine. It will be updated to 5th edition Hero as soon as I have a copy.
The Rodericks. A father-daughter pair of Champions characters.
Usable Against Others - Diced Effect. This is a new Hero System power advantage.
Side Effects Revisited. A modification of the Side Effects Advantage.
Magic Levels in the Hero System. This is an idea similar to GURPS's mana levels, implemented in Hero.
Illusion Disguise. A new Advantage for Mental Illusions. Soon to appear in Digital Hero at Hero Games' official web site!
Improvisational Magic in the Hero System. Expanded from the concepts in my earlier "Improvisational Magic in Fantasy Hero" Usenet posting (archived by Juha Vesanto).
FUDGE Super Powers. Super powers rules for the FUDGE RPG.
Fudge Magic With Feeling - A homebrew magical system translated into Fudge. Incomplete but possibly useful.
Fudge Ghostbusters - A translation of the Ghostbusters RPG into Fudge.