Here is your definitive answer, on what you can expect out of the Nvidia 920m for games.
It will handle modern games (as of 2014/2015) in low settings.
Low resolution, with most of the game, graphical details on low. with little anti aliasing.
I would expect the 920m to have a harder time trying to run Arma 3 to be honest. I think you will find that CS GO will run a bit better.
Frame rate expectations at a rough guess depending on resolution 28 to 36 fps.