Rating
Nobody has played it on Walnut yet, so it has no medal.
Installation
With the buttons above: Install, then Add game files... and pick your copy of Day of the Tentacle: the disc in the drive, an ISO, BIN/CUE or MDF image, an installer or a folder. The game data is not part of the package, and Walnut does not offer it.
What works: TENTACLE.000, TENTACLE.001 and MONSTER.SOU from the CD (the talkie) or the floppy release, in English, German, Spanish, French or Italian: the CD, an installed copy or the floppies' files copied to a folder.
More ways (a terminal, game-data-packager on any Debian system, copying the files by hand): Guides.
The game's home page: https://wiki.scummvm.org/index.php?title=Day_of_the_Tentacle. License: GPL-3.0-or-later engine (ScummVM), commercial game data.