Death Gate now on GOG (now removed) but Eric the Unready added.

While it's not Sierra or Lucasarts, but Legend Entertainment had some fun games too, they had several more like Callahan's Crosstime Saloon and Shannara, which i assume would also come eventually.
But also titles like Spellcasting 101, 201 and 301, Gateway 1 & 2 and Timequest (which i found more difficult and had dead ends).

Now i originally wanted to bump this, because both were from Legend Entertainment, but it seems Death Gate got removed in the meantime (which is a pity), hopefully that can come back again at some point.

https://www.gog.com/game/eric_the_unready
https://www.gog.com/game/death_gate

Here is to hoping they come on steam too, if you never played them and love adventure games, i can really recommend them.