I ordered and bought 'Heretic + Hexen' it's day of release here on GOG. But for individual files, and I do NOT use Galaxy (whatever that is), the installer says 'Install Medusa' when activated. What gives? And why is no support even listed yet for a game released today? HELLO? ARE YOU THERE?!
I hope I can get my WRONG GAME replaced by the one I bought here; and anyone else should maybe check your install files too: you may be screwed, like I have been today. :-(

Update: The offline installer is misnamed 'Medusa' at install, but it did install my 'Heretic + Hexen' game after-all. It was the wrong installer-name though, so should be updated soon to fix this; I don't install unknown software on my pc. ENJOY! lol

As you say, it is misnamed in the installer, but there does appear to be an issue. The enhancement settings appear to be missing (enhanced levels, enemies, weapons), no co-op menu. and you can see in the installation folder an executable with the Medusa name. I suspect Medusa was the WIP codename for the project and that we have a pre-release version. GmanLives has a YouTube review that demonstrates these enhancement settings.

Edit: The enhancement settings are found by pressing Tab when choosing a difficulty setting for a new game, so it all looks fine and it might just be that Medusa is a leftover from the development process.

Holy God...