Spacewar! was a F2P PvP game with no microtransactions and no battle pass. Although it's hard to quantify exact player numbers (it precedes Steam charts), for a while it was the most played videogame in the world.
Its real-time graphics and multiplayer combat were very influential, and widely copied by many other games.
for a while it was the most played videogame in the world.
I see what you did there!
Space War history
SpaceWar is the first game to be frequently ported to different computers, back when computers took up a big portion of the room they sat it, and when "porting" was practically re-coding, from scratch, in Assembler.