arma

Sounds like a testing platform for ARMA 4.

In celebration of selling 4 million copies on Steam, Arma 3 is having a free to play weekend, as well as being on sale for $13.59, which is 66% off, and all Arma 3 DLC is on sale as well. DSOGaming has done a good writeup of Arma 3 if you don't know what the game is about, you can pick up Arma 3...

It is 50% off on Steam and has 50vs50 player servers. Gameplay is similar to ArmA but not as many vehicles.