Quantum Link is about a decade before my time, but I remember connecting to BBSes in the 1990s, and playing Doom over modems. Good times.
Heh, here's a tidbit about PvP in Habitat, an early MMO that ran on Quantum Link:
At first, during early testing, we found out that people were taking stuff out of others hands and shooting people in their own homes. We changed the system to allow thievery and gunplay only in non-city regions.PvP game designers encountering PvP players, something we've been able to count on for the last 30 years.
Edit: Pallais found a really nice paper on Habitat, written in 1990. It's an interesting read.