I want to play CS:GO or other related games on my MacOS but with 2 monitors at the same time. But the game will launch only on 1 of the monitors that I choose from the System Preferences. Any idea or knowledge about this problem?
However, CS GO does not support multiple monitors on its own, so it's at your own risk. You would need to use 3rd party tools and you never know how VAC reacts on those things. It works, but might get you banned. Beware!
Here is a list of games with some info about their multi monitor support.
CS:GO is made for only one monitor.
With two monitors your crosshair would be between the monitors... pretty hard to aim with bezels splitting up the crosshair, so it makes sense to play CS:GO on one monitor.
What can you do: You can use your second monitor to show a picture of the current map for a better overview or to show a strategy-guide. (Just examples, feel free to open up what you want.)
Other games: This affects a lot of games. Maybe you can find a game which supports a dual monitor setup, showing up some stats or infos on your other monitor. Just take a look at the videosettings of your game.