Quoting: utxDoes anyone know how old linux games usually worked during the CD days?(90's - 2000's). What type of file it used? Was it an installer? Was it just ran from the cd?

I think you should be a bit more specific in which game you are interested in.

Quoting: utxDoes anyone know how old linux games usually worked during the CD days?(90's - 2000's). What type of file it used? Was it an installer?

Many popular games used a Loki installer, or BitRock InstallBuilder. You have to understand that many games for Linux were available only as the digital versions.

It depended on the game (or rather perhaps the publisher).

Some, like Loki, had an installer on the CD called loki_setup. A modern version of this, MojoSetup, is still used for many native Linux games. Everything on GOG for example.

(If you do go back in time to run such an installer, remember to manually run "eject /dev/cdrom" to get your disc out, because pressing the physical eject button on the drive did zilch back in the day...)

Others, like id Software, was a more unofficial affair. It was usually either an installer or a compressed archive with game binaries to download and use with the Windows release of the game. You had to finger John Carmack to find out what was new in the world of Quake and then download the new patch with FTP.