In 1977 or thereabouts, I was a co-op student at Xerox' Webster, NY Research Center. At lunchtime, I had access to an Alto, and spent far too much time playing MazeWar, a networked multi-player real-time 3D-perspective game wherein the players navigated a maze (displayed as wireframe 3D with an overhead map at the side), finding other players (who appeared as giant floating eyeballs) and zapping them. Once zapped, you respawned elsewhere in the maze and attempted to sneak up on your opponent and return the favor.
The graphics were extremely simple; there was no detail in the walls, just lines showing the edges, and player positions were limited to the center of each grid square; player movement was in discrete jumps. All of this was done to reduce the computational load for the graphics, of course. As a result, the system was very responsive, and the experience was quite immersive.