If I recall correctly all quake games had a scripting language and an "autoexec.cfg" file on the "baseq2" ( in your case ) would be executed automatically on the game start.

For an endless loop all you need to do is to execute a file from itsself, so for an endles loop it should be something like:

1demomap demoX
2exec autoexec.cfg

where demoX is the demo you want to play forever, or until a stack overflow in the game, but that should happen after several hours, if ever.

EDIT: More about Quake2 console:
https://www.eecis.udel.edu/~portnoi/quake/quakeiicom.html

Download the 3Finger's crusher.dm2 Crusher demo at: https://www.fileplanet.com/28888/20000/filein … usher-Benchmark

There is also a massive1 from 3 fingers: https://www.fileplanet.com/28889/20000/filein … sive1-Benchmark

-Put the demo file in the /baseq2/demos folder.
-Run Quake2, open up the console.
-Type timedemo 1
-Type cl_maxfps 999
-Type demomap crusher.dm2
-Sit back and laugh at the crazy fps you get on a modern pc.

This came up looking for looping but says quake 3. dunno if it works in q2

Put this into your autoexec.cfg:

set loop "s_initsound 0 ; snd_restart ; timedemo 1 ; demo <demoname> ; set nextdemo vstr loop"

Start Q3 and type "vstr loop" from the console.

Thank you both. Will try this weekend

I tried just running the crusher demo from console command to make sure things were going to work and I got the following message:

ERROR: Server returned version 30, not 26

Any ideas?

Most likely the demo is too old for the version of the game you are running.