To use the program you will need the original files of the game you want to play, which you look for on ScummVM and add to your library. Once there, you can change the graphic and audio configurations, and even customize the way you want to play the game using post-processing filters.
The list of compatible games is endless, and with every new version, new graphic engines are added in addition to the well-known Scumm system developed by LucasArts and used in games like Monkey Island, Day of the Tentacle, or Sam & Max; or the SCI that Sierra used in the King's Quest saga, just to mention a few. What's really interesting is that many of these games, considered now 'abandonware', have been distributed freely by their original creators, so you can download and play games like Temptress, DreamWeb or Flight of the Amazon Queen, all of which are available on Uptodown.
ScummVM is a great tool to remember old classics on modern computers, with the extra advantage of modifying aspects of the graphics and sounds through an easy interface.