So these are my settings,
To note here, I do run at at high bit rate, so play with this for your needs.
To add games as sources, you want to select from OBS sources Window Capture, and this is how I have one of my games set.
Again, before you add this, have the game in question running first, if you want to capture HDR footage, uncheck force SDR capture.
you would need to do this for every game you care about recording for.
I have mine currently looking like this
now if you just want to record everything, you can just select display capture and select your monitor from the properties section in the sources section and this will basically record everything OBS sees on your monitor, so if you alt tab a lot ( like I do ) it will capture that as well.
The window capture source option will still let you record the game even if you alt tab.