DreamZZT is an open-source ZZT engine for Mac OS X, Microsoft Windows, Linux, and the SEGA Dreamcast. ZZT was an ANSI-based game creation system created by Epic Megagames’ Tim Sweeny in 1990. The original release included 6 worlds, including the shareware world The Town of ZZT. It also included a built-in game editor, allowing for the creation of new games.

Not quite an emulator, but most matching with this category.