MegaZeux

MegaZeux, or MZX, is a game creation system (GCS) inspired by Tim Sweeney/Epic MegaGames' classic shareware game ZZT. MegaZeux was created in late 1994 by Alexis Janson, who formed her own company, Software Visions (now defunct). Like ZZT, MZX was originally released as  shareware and the world editor portion of the program was included for free, allowing third parties to create their own worlds without even registering.

MZX is officially supported on Windows (Win95 and higher), Linux, Mac OS X, Wii, GP2X, PSP, and the DS, but has been ported to other platforms such as AmigaOS 4, OpenBSD, FreeBSD, OpenSolaris, Haiku and Android.

MZX improved on ZZT in almost every aspect:

MegaZeux was shareware during the time Janson maintained the code. MZX came with a default game, Caverns of Zeux. This was a sequel to an earlier Software Visions shareware game, Labrynth of Zeux; a platformer about a theologian/archeologist named Vince Louis who retrieves the magical Silver Staff from the ancient Labrynth of Zeux. In Caverns, Vince has just retrieved the Staff when it emits beams of magical power and teleports him into a vast network of caverns filled with traps, puzzles, and monsters. As incentive for registration, players could purchase the other three Zeux games (Chronos Stasis, Forest of Ruin, and Catacombs of Zeux), all of which dealt with Vince's quest to return home.