This is just a FYI if someone else runs into this.
I installed Deponia 4 via the galaxy client on a Macbook white 2009, still running OS X 10.9.
On start it gave me the init error, saying some game file is corrupted.
If you google the error you'll see some misleading results about your video card not supporting a new enough OpenGL version, but in this case i guess some game file really IS corrupted.
Removing the game from the galaxy client and installing via the directly downloadable .pkg from gog.com results in a working Deponia 4.