the main function of a multiplayer game server is to contain the game state. Depending on the game, it may also run a simulation. You couldn't, for example, wri

the main function of a multiplayer game server is to contain the game state. Depending on the game, it may also run a simulation. You couldn't, for example, write a database record every time someone shot a gun in an FPS, the whole thing would come to a crawl. And game clients generally only care about the present. Only the current game state is of interest to the client in most situations; the past is rarely queried. The outliers here are things that are naturally transactional and persistent like character progression and item ownership; those things you'd stick in a database.