Those games use Adobe Shockwave and that product was discontinued in 2017 for Mac, and 2019 for Windows. I personally would NOT recommend you install this plugin just to play these games, you can find alternatives that employ HTML5 or other technologies to play the games elsewhere.
If you want to play a game of "Space Invaders" on your Mac, download and install the free "GZDoom", Doom 2 free demo, and the "Space Invaders" wad. I guarantee it will keep you up for hours as you're killed and come back to life numerous times until you finish the game. It has 10 levels, each one more difficult as you progress. Took me a week to get thru all of them.
Here is the link for GZDoom: ZDoom - Downloads It's made for the Mac and is 64 bit in case you're running Catalina. You will also need an original copy of Doom 2 to use.
All seems a bit complicated to set up and get running but it's actually very easy and runs real well on a Mac. Actually much better than the original DOS or Windows versions.
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