Can't seem to find anything like this in the support area so I thought I'd try here. I downloaded Mac OSX Installers for Deponia 2 + 3. They are .dmg files and when I click on them I get the error message ' The following disk images couldn't be opened' and it shows 'deponia_2_1.1.0.4.dmg - image not recognized'. I got the same error for The Witcher 2 installer I downloaded. The Costume Quest installer worked fine however.

Anyone got any idea how I can fix this?

Cheers

This looks like a corrupt download. deponia_2_1.1.0.4.dmg is probably broken.
I'd re-download it and to make sure it isn't broken again, use GOG's Downloader, it has got an error protection.

Before, you can also try rebooting your system, maybe there's just something locked up.