I just discovered that the U.S. Army is one of the oldest video game developers ever.
In 1960, they developed LOGSIM-WC, and it is something else:
LOGSIM-WC (Logistical Simulation Wholesale Computer-assisted) is a serious game used by the US Army as a simulation for logistics. The game is intended to be played by higher administration, senior officers and civilians involved in the supply chain. The game simulates the operation of a National Inventory Control Point and measures the effectiveness of the supply by the players.
It ran on an IBM RAMAC-305 and had multiplayer aupport for up to eight players.
Interesting thing is that this isn’t the only game the U.S. Army has made. They made a whole series of FPS games called America’s Army that was used for recruitment.