Fuckit, if anything more fancy than HTML + CGI is needed, there’s always VRML.

…holy shit, it just dawned on me… VRML + CGI? Today’s PCs should have no issue rendering it, and server-side should be the same as any other CGI page. I gotta do some experimenting with this.

UPDATE: I actually did some research into this, and the possibilities are actually quite extensive. In theory it should be possible to make an extremely basic multiplayer FPS game.

Fortran. At least it was comprehensible to a human brain once upon a time. And probably efficiently written.