Probably a stupid question, but how do you access the expansion missions? Do you need to complete the base game first or something?

Not planning to play the missions yet, just want to make sure that the expansion is actually installed, as it's not mentioned anywhere in menus/etc.

It is on the main menu screen. Here is a screenshot:

http://cdn.akamai.steamstatic.com/steam/apps/92803/ss_d24ca934cf557b0404a47ce0e2c96007c1a2dc06.600x338.jpg?t=1388429327

Look at the right hand porthole. You click that sun to access the 63 Corvi missions, and you don't need to complete the main game first.

Hrrm., My game screen looks like this:
http://i.imgur.com/gMVVmWN.jpg
Clicking on that sun does nothing. Looks like the Linux version does not include the expansion. Time to file a ticket, I guess.

You are right. I installed the Windows version and it has the expansion, whereas the Linux version doesn't.

Did you receive an answer to your ticket? It would be very interesting, why the Linux package from gog does not contain the Corvi missions while the Windows version does.

(On the other hand ... I just copied the files of the Windows version missing from the Linux version into the appropriate folder and it works, too.)

Thank you. You're right, that doesn't sound promising. I suppose 'product team' means someone at gog.com? Because otherwise they'd have said 'developer'.

Copying the files was my solution at least. I even made a tarball in order to have it ready for the next time I have to install it.

It still seems to be the only way. I'm about to finish the game's normal campaign and was wondering if there was an expansion and then realized I was supposed to have the DLC but couldn't find anything in the game related to it. Thanks for letting me (and anybody else playing the Linux version) know where to find it. Hopefully they'll get that fixed in the future.

Would it be productive to bring up the issue with GOG again? It's 8 months later and at least my install of SpaceChem on Linux doesn't have the expansion as far as I can tell (and I just re-downloaded it using the new GOG installer). Digging through the Windows install doesn't seem like a practical solution. How would I go about filing a ticket?

Follow any of the multitude of Support links on the site, choosing Spacechem if needed, and click on I can't find solution for my problem.

Submitted, thanks!

Is the DLC still missing from the linux version?

Late response ... the 63 Corvi DLC is now also part of the Linux version (tested with the 1016 update).

I still love this game even after some eight years.

Thank you for the information. ^_^