These games were released for free as part of SEGA's 60th anniversary in 2020 and were delisted after only a few days.
But you can still install them by pasting these links into your browser. It will tell Steam to install those games and add them to your library. The numbers in the links are simply the Steam ID's for the games in question. Even if you choose to not install them, they'll still be added to your account.
Streets of Kamurocho: steam://install/1368430
Armor of Heroes: steam://install/1368440
Endless Zone: steam://install/1368450
Golden Axed: A Cancelled Prototype: steam://install/1368460
If you think that's shady to paste links in your browser, then go to SteamDB and find those games and click the "launch" button and it will have the same result.
