How do I install this in Debian?

[grib]

64-bit arch?

If so, you need to install the ia32 versions of the necessary libs. The Penumbra games are 32-bit binaries.

Depending on your debian version, the instructions are different (there's currently a transition ongoing in unstable to autogenerating the ia32-on-64-bit libs from the i386 package) but you can try 'apt-cache search ia32 glx' and see what comes up on your distro.

You should have the relevant libs in /usr/lib32 once you are done, and 'ldd' on the game binary should show the libs resolved from /usr/lib32.

Good luck!