alsamixergui says
function snd_ctl_open failed for default: No such file or directory
I cant test openarena
I guess I did not add user to audio group !!!
You can add users to the group. For example:
gpasswd -a USER GROUP
For more information read this text.
thats what I needed 
I added audio and video and I could play openarena
but it looked like the video driver is not installed
It has bad graphic and low framerate.
Playing videos on youtube are also a problem, like the vga is badly installed.
Is there something else I forgot about video card to set ?
Since I can play openarena in sabayon, I suppose I have to set or switch something here.
Do I see right that there are two versions of driver for nvidia5500 ?
173.14.28 and 173.14.30
Looks like I have installed 173.14.28
should not I use 173.14.30 instead ?
Show output <>.
Available OpenGL implementations:
[1] nvidia *
[2] xorg-x11
Try to download the latest Stage-image. Here you can choose at boot time video driver among the “nvidia” and “novueau”.
Do you mean this http://distfiles.gentoo.org/releases/x86/autobuilds/current-stage3/ ?
And unpack to / (root) ?
I think I already did it, because 11.3 did not install nvidia173 and 11.6 does automaticaly
OK, You can try to select a nouveau video driver.
Can I just change the boot kernel option of current system ?
there is calculate=video:nvidia
and set to calculate=video:nouveau ?
You can change video driver by command:
cl-install --live --set os_install_x11_video_drv=nouveau
and reboot.