Darkdragon, my experience is that nvidia's drivers are far better for anything written to standards, while ATI does a lot of work making theirs work with particular games. Seeing as ATI is never going to check them against DF, you're out of luck there. I prefer to stay away from them.
Regardless of your opinion toward a company, it's best to work on ways to make a game perform on both types of graphics cards available.
But if that's your opinion I guess I won't be donating any time soon.
I kinda get the sense you're jumping to conclusions. As it stands, you're the only person with an ATI card, that I'm aware of, that has complained, so that immediately points to some form of problem on your end. And complaining that the game doesn't work on ATI cards isn't accurate, either. It runs, just not as well. And you can't really fault Baughn for using OpenGL's standard, or at least I'm assuming he is. It's not his fault if ATI cards don't have great support for OpenGL. And changing engines isn't really an option. DirectX limits the game to Windows.
Outta curiosity, what are your system specs, anyway?
On that note, I've run the D series exclusively on ATI cards on my Desktop Linux Box (my ancient intel / intel laptop would melt) and I've had good luck with the native builds vs R600 integrated (3xxx) and R700 discrete (4xxx) class ATI / AMD cards with the closed FGLRX driver and the new open RADEON driver in Debian Unstable.
Here's my specs:
OS:
-Using Debian Unstable, currently with the open RADEON driver (I believe FGLRX is in a PITA state in Unstable ATM).
HW:
-A dual core Athlon 6000+, with 2 GB of DDR 2 800, with an ATI/AMD Radeon 43xx passively cooled video card.
FORT (D18):
-A 6x6 site with moving magma, a brook, populated underground river, pit, and still hidden HFS, a population of 40, with 20 pets, and a fair bit of wildlife, will run at about 50 (14) FPS on STANDARD with a GFPS of 15 while 'windowed and maximized' with 16 x 16(?) tiles.
I consider the performance 'acceptable' even though it is lower than I recall with the FGLRX (closed) driver. ATI's closed driver actually advertises support for 'very recent' open GL versions, and historically, on Linux, the problem hasn't been ATI's Open GL, but version matching Xorg and the Kernel, combined with grossly slow desktop rendering, hard lockups, and chronic bugs.
I say this once to Linux ATI users: ONLY USE FGLRX UNTIL THE OPEN DRIVER IS ADEQUATE ON YOUR HW. Unless you really need ATI's Open GL performance, and you don't for DF, run away from FGLRX as fast as you can. The next round of distro releases should have good open support for everything up to about R700 class cards / chips.