Prison Escape is not ever fun, wtf?
it was a "prison escape" in name, but played way more like a specialized TDM. 4 guards had to hold off waves of prisoners from escaping. it's not some sort of subjective-rules gamemode - guards shoot prisoners on sight, and prisoners have very clear goals (and need teamwork to complete any of them)
even disregarding that server (which was incredibly popular, as well as my remake), there's plenty of other servers like heed's servers, jorgur's dogfight and RPG, bluzone, crown's pb, boss battles, and countless others. they just came alongside a lot of average servers. try naming some servers you remember pre-UPNP hosting that you actually liked/loved.
if anything your nostalgia filters are on too high cause pre-2011/upnp hosting, most "good" servers entailed using a bunch of separate mods to cobble together a build and a game. it was only after 2011/upnp hosting that full gamemodes started to come into existence, where mods were custom made or tailored to the server content, or the vision of the host.