The X driver, as per my post above. In-game, it was set to "OpenGL".

Well, my personal problem has been solved. If I can help debugging some general issue by providing additional information or testing things, I will be glad to.

Ah! With software rendering, it all looks much clearer, thank you!

For the sake of completeness, lspci lists the graphics card as this:

VGA compatible controller: ATI Technologies Inc RV620 LE [Radeon HD 3450]

The Xorg driver in use is "radeon".

This is on Debian Stable with OpenGL rendering (according to the options screen; I have not changed any settings there).

Sure, here is a picture of the lift in motion:

I'm using ResidualVM 0.1.1 (Feb 10 2013 10:08:41) to play Grim Fandango. There are many graphical glitches, but so far, the game remained playable. I have progressed to year 2 and now I'm trying to stop the lift. From back when I played the game 15 years ago, I remember that the lift somehow closed ...