Have you tried playing with the settings in:
~/.frozenbyte/Trine2/options.txt
If you run the game in fullscreen, I would take a look at ForceFullscreenWidth and ForceFullscreenHeight :)
Have you reported this to the game developer? That will likely get more attention than an issue here.
@pete-h worked like a charm, thanks.
Very cool, game runs beautifully at 2560x1600, good to see.
Nothing extracted yet.
Either the linux client maxes at 1920x1200 or it is detecting the resolution of my smaller 24"es and not my 30".
Otherwise impressed that I can max out the anti-aliasing and basic settings and play at solid framerate.
[machine info: http://paste.kde.org/669494/raw/]