Go check it out.

https://www.seinfeldgame.com/

I don't know if this is official but... here you have...
https://wiw.org/~jess/sq6demodl.html

Another find...
http://cd.textfiles.com/sprintos6/GAMEDEMO/
http://www.sierrahelp.com/Misc/Demos.html

Some demo versions are different from the ones you have... there's one, at least, that you don't have... Space Quest V: The Next Mutation.

Enjoy

This one was easy to find...
https://archive.org/details/The7thGuest_1020 :)

This release completely messed up the 3DO version of "The Lost Files of Sherlock Holmes: The Case of the Serrated Scalpel... doesn't run anymore. :cry:

Thankx!

Try this! http://www112.zippyshare.com/v/Y0RK3615/file.html

Has anyone seen this? Is this the right place for this matter?

DK:!n369trHOihAwN5cNuIBp7FMPzWRWXqocqbH8sewwsvs

Please add support to Maniac Mansion (Atari ST Demo), below is the link to get it! Feel free to add it to your "Demo" section.

Thankx!

https://mega.nz/#!JE0zmSiR