Did you find the reason, why sound was not working previously?
There is an abundance of games hosted over at Macintoshgarden, much depends on what you are looking for.
There are screenshot apps for Mac OS, but usually you´ll be fine with Command-Shift-3 for your whole Mac screen.
I´m not sure whether Command-Shift-4 for a crosshair to select an area was available in the MacOS all the time, just try yourself.
With a PC keyboard in emulation, Mac-Command (⌘) is usually left-alt, if no custom key mapping is active.
You may have guessed, that Mac-Alt is on the Windows key in such setup.
More key combos a described here: https://support.apple.com/en-us/HT201236