ScummVM is a program which allows you to run certain classic graphical adventure and role-playing games, provided you already have their data files. The clever part about this: ScummVM just replaces the executables shipped with the games, allowing you to play them on systems for which they were never designed! ScummVM is a complete rewrite of these games' executables and is not an emulator.
You can find a full list with details on which games are supported and how well on the [compatibility page](/compatibility/). ScummVM is continually improving, so check back often. Among the systems on which you can play those games are Windows, Linux, macOS, iOS, Android, PS Vita, Switch, Dreamcast, AmigaOS, Atari/FreeMiNT, RISC OS, Haiku, PSP, PS3, Maemo, GCW Zero and many more...