Ok, I'll grant that it's somewhat hard to ensure all the games work in these conditions while considering a wide variety of graphics hardware... and a 30 day money back guarantee to honor ;). Point taken.

Maybe it would be nicer to explicitly tell that the game was tested and found to not work with some driver combination. "Not supported" can mean almost anything.

What about the r600 driver (on mesa 10.4 or newer)? I hope it works, because the driver catalyst-legacy stopped working years ago on modern linux distros. It's not like if we can choose to use the open source driver or not (But I have to say it is pretty good).

It does not work for me (Radeon HD 6450), not with mesa 10.3 or 10.4.

I just tried it, and the game works as it should on my card (hd mobility radeon hd 4200) using the r600 driver, mesa 10.4, using Manjaro linux, kernel 3.18. But I'm not trying the gog version (steam) if that somehow matters. In your case at least you can still use the catalyst driver, maybe thats a bug than will be fixed in the next version (or update) of mesa.

Thanks, but using the catalyst driver is not really an option for me (I'm also using other software that doesn't exactly see eye to eye with catalyst).

I'm already on mesa 10.4. I'll give the 3.18 kernel a try, perhaps that has some mesa-10.4-required magic.

For me it says:

Grim Fandango can’t run becaused required OpenGL features aren’t available. Make sure the latest graphics card drivers are installed.

when launched with start.sh, but if you go into game/bin and launch GrimFandango it starts up with no problems and seems to run just fine. Very strange!

OpenGL renderer string: Gallium 0.4 on AMD CAPE VERDE
OpenGL core profile version string: 3.3 (Core Profile) Mesa 10.6.0-devel (git-3f1e128 2015-02-13 utopic-oibaf-ppa)

start.sh is a wrapper startup script build by GOG. You might want to raise this issue with support, they might clarity why you are seeing that message though you clearly meet the OpenGL version requirements.

start.sh fails for me too:
Running Grim Fandango Remastered
Command line arg: ./GrimFandango
Absolute executable path: /home/jr/Grim Fandango Remastered/game/bin/GrimFandango
Leaving working directory as: /home/jr/Grim Fandango Remastered/game/bin
libGL error: unable to load driver: radeonsi_dri.so
libGL error: driver pointer missing
libGL error: failed to load driver: radeonsi
libGL error: unable to load driver: swrast_dri.so
libGL error: failed to load driver: swrast

But going into game/bin and running it directly via "./GrimFandango" works fine.

I pretty sure the problem is the same as running steam with the steam runtime time: You get all sorts of libraries preloaded, which do more harm than good. Double Fine should add an option to switch between running directly or using the included libs.

For the record: My system has a radeon 7950 and the newest mesa and kernel 3.19. (important parts of glxinfo below):

OpenGL vendor string: X.Org
OpenGL renderer string: Gallium 0.4 on AMD TAHITI
OpenGL core profile version string: 3.3 (Core Profile) Mesa 10.3.7
OpenGL core profile shading language version string: 3.30
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:

I can confirm the same. In fact, simply deleting the amd64 and i386 folders in Remastered/game/bin (containing all or most of the shipped steam runtime libraries) will allow the game to work perfectly, even from GOG's start.sh script.

There's really no major technical reason why this game shouldn't work on the open source drivers, OpenGL 3.3 has been supported perfectly well for quite a long time now and the vast majority of GL 3.3 games work without issue. It appears ignornace on the part of GOG's testers is why they didn't catch why this game won't work (or they're not bothered about the actual why, just that it didn't work).

EDIT: nevermind, I don't think my GPU would meet the requirements anyway

Wait a minute I found out that my ATI Mobility Radeon HD 3650 supports OpenGL 3.3 after all. So I'm wondering again if the game will still work under the open source drivers using the GrimFandango executable instead of start.sh?