Pulseaudio messes with game sounds quite a bit. My usual solution is to uninstall pulseaudio and just use alsa instead, but because of the way that ubuntu has tied pulseaudio into everything uninstalling pulseaudio can be a messy experience.
The simplest solution is to just run:
sudo apt-get remove --purge pulseaudio
sudo apt-get remove --purge pulseaudio-*
sudo apt-get install esound
The main problem for me with this approach is that it breaks sound in the Gnome Media Player. The solution for this is to just use vlc ( `sudo apt-get install vlc` ) which works like a charm. If not for pulseaudio, ubuntu would be the perfect distro for me. Hopefully the pulseaudio team gets all of these bugs worked out soon.
Edit: Please note, I am not responsible for any issues that you may face due to uninstalling pulseaudio! However, it has worked fine on my 5 systems so far...
