Here are some games by me, that challenges could be made for. Somewhere it said that challenges would be worth 10 XP to anyone who completed one.
Piggy's Metropolis 1.05:
This is a game where you wonder about in a city. it has many secrets. There are many ways to make challenges for this.
http://www.fast-files.com/getfile.aspx?file=24246Energy Ball IV:
The fourth in the energy ball series. There are 50 levels, and several challenges of varying difficulties could be made for it.
http://www.fast-files.com/getfile.aspx?file=24247Fuzzle Quest 2:
A nice platformer with a lot of potential challenges and replay value.
http://www.fast-files.com/getfile.aspx?file=24251That's all of the challenge games, however, I'd like to show you guys my fake OS.
Latest stable version:
CJFGX 4.75: Raptor blackbird!!
http://www.fast-files.com/getfile.aspx?file=24252alternatively, if you have Game Maker 7.0 Pro(Game Maker 7.0 Lite, the free version, might work, but I wouldn't count on it), You may download CJFGX 5.0 Beta 1, and add your own changes:
http://www.fast-files.com/getfile.aspx?file=24253If you wish to use the browser, Crystalfire, that comes with CJFGX, you will need the following file in the same folder as CJFGX if you are using version 4.25(Raptor plus) or later:
http://www.fast-files.com/getfile.aspx?file=24254and finally, a fully open source version of CJFGX 4.75(Raptor blackbird)
http://www.fast-files.com/getfile.aspx?file=24255game maker 7.0 lite can be gotten for free from
www.yoyogames.com, but game maker 7.0 pro you have to pay 20 dollars for.