abandonware, n.: out-of-print video and computer games, as collected and played by "classic" games enthusiasts, on refurbished systems or on emulators. [GJ1]
Addendum: MAME, the "Multiple Arcade Machine Emulator," and Stella, an Atari 2600 emulator are two of the larger examples of fan-made, fan-supported emulators for playing classic games. [MW]