Came here to make the same comment.

I also played - I guess back in the late 90's, with an autonomous Asteroids-like game where you'd write code to control your "space ship" that had "radar" to show you nearby opponents and had pretty much just Asteroid-like controls, which ran as a networked screensaver. It came out of a bunch of people working at Canon - a friend of mine worked there writing printer drivers...)

(Now I'm wondering what you'd get if you let loose inside a modern device, like a cellphone for example, with two opposing bits of fighting code with full root access, but strictly equally time and resource shared? Would Core War even make sense any more with Gigs of ram, hundreds of gigs of flash, asnf stuff like wifi and bluetooth?)

You probably played crobots: https://tpoindex.github.io/crobots/ It was quite popular at that time!

Thanks I just looked into this, I've never heard of it before.

Here is more on its language http://vyznev.net/corewar/guide.html

This is nuts!