I played this somewhere in the early 90s, I think, downloaded off of a Bulletin Board System and played via a direct connection over the phone lines the twice I actually got to play. It might have been run on Windows 3.11, although that would have been the right timeframe for us to have moved on to Windows 95. The character plays a two-legged robot or mechsuit with weapons. I remember one of them was a laser gun that showed up as two lines that converged from akimbo arms to converge on a point in front of the player. Their opponent is another robot which differs only in color (I think red and blue?). They move around in a maze, trying to destroy each other. The game was in pseudo-3D, I think using layered sprites to represent the corridors. Movement was from space to space, and turning happened at 90 degree intervals. I can't remember what other weapons might have been used, although I want to say there was another weapon that was effective at a distance (missiles?), but was much slower, allowing for a bit of balance between trying to tag someone at the end of a hallway and then ducking away versus sneaking up and blasting away at them.
I don't remember much about the interface. I don't know if there was a map of the maze being displayed to help players find their way.
There was no real offline play, at least in the shareware version I played, with a completely inert opponent to be found and defeated.
I was trying to find a way to describe the graphics style, and came upon Maze Wars, which is kind of a direct predecessor to this game, with this one having similar gameplay, but a more limited amount of people participating, and somewhat advanced graphics.
Rough idea of what the robots were styled like
Like this, but colored, and only seen from front, back, and side views.