I run lots of GOG games on Linux - including several DOSBox games successfully. But when starting screamer, I first see the intro driving movie of some cars, but when trying to start, only the message "Insert Data Disk" (or similar, as I can't get out of this anymore) appears ... it should be DRM free, right?

Okay, the thread "Screamer Under Linux via DosBox" solved this. But audio is still missing and the whole game is extremely slow ... unplayable as it is just a diashow.

Thread "Too fast for Screamer" solved the issue of performance: setting

cycles=150000

in dosboxScreamer.conf made the game smooth.

The original Screamer required the CD for music, the GOG version uses Dosbox's CD-ROM emulation for that. So you have to figure out how to configure it with imagemount, the easiest way would be copy it from the .conf file GOG used for windows.
As for speed, best is to use core=dynamic I think.

It's probably best to ask this on the VOGONS forum, they have more knowlegde about this as there gather the makers of dosbox.
They have some good guides on how to setup games on Linux too.

Thanks for the info.