Ok more info:
What I did
unpacked; cd ufoai/ ; ./ufo
What resulted:
Adding game dir: ./base
using /home/marten/.ufoai/base for writing
Adding game dir: /home/marten/.ufoai/base
execing default.cfg
couldn't exec config.cfg
execing keys.cfg
Console initialized.
------- sound initialization -------
Using Alsa
Using sounddevice "default" - if you have problems with this try to set the cvar snddevice to a appropriate alsa-devicesound sampling rate: 48000
------------------------------------
------- Loading ref_glx.so -------
LoadLibrary("///ref_glx.so")
ref_gl version: GL 0.12
Segmentation fault
I haven't tried the trunk yet, but i'll download it when I get the time.