Back in 2008 I started coding (or just plain drag-and-dropping at first) in Gamemaker. It basically taught me how coding languages and objects worked. I also made some pretty simple games/programs with it over time. All the programs listed below were made with GameMaker 7, which was the latest version at the time I was using it. I won't make any more games/programs with it due to it's limitations.
This has been the first thing you could really call a game that I made myself. It's still unfinished, and it won't ever be, but all the main coding is there. To finish it I only had to put in some more content (more objects, levels), but I never came up with new ideas. Eventually I got bored of trying to come up with new stuff and creating levels, so I stopped working on it.
In the game itself you have to get crates into a dropbox using conveyors and other objects you can place. It also has a constructor to create and test your own levels with. The only thing I did not make myself for this game was the music (which is evident).
Download game (.exe)
I have helped the developer of this game by coding part of the AI of the enemies.
That's basically it, it turned out to be quite a funny game to play as well.
In the game you control a spaceship, and you must defend your core/base.
The enemies will try to take down your shields and base and you should kill them before they do.
An idea I worked on for a day. It's more screensaver than game. It's a screensaver with some options you can edit when it's running.
It's a black screen at first, use [Enter] to bring up an info display.
Use R/Y/G/W/B to toggle red/yellow/green/white/blue colors respectively.
+ & - to toggle the speed of object creation.
P to pause.
DTM is a tool I made for dungeoneering in Runescape. It's an interactive multiplayer map that you can use to keep track of where all the obstacles, doors, paths, etc. are in the current dungeon. I stopped developing it after I noticed it was too tedious and slowing to keep updating it while also completing a dungeon. I still think the idea behind the tool is awesome though =)
My attempt at the same idea a few months before that can be downloaded here (21-6-2010). This one failed because I used the built-in networking system, which did not work at all. I discovered that after I had been working on it for a long time though =S
Beware the spamshockintro.