Step 1: Use a prepaid Visa card to buy a steam game. Do not use your own account, create a fake one.
Step 2: Wait for it complete downloading, Open it once but close immediately after the game launches properly.
Step 3: Download Smart Steam Emulator 143 (Link Below).
Step 4: Copy the game folder from your steam common file. Copy the entire folder to a different folder outside steam.
Step 5: Add the game to the Smart Steam Emulator 143 and add the steam app id and nothing else.
Step 6: Open the game, let it connect the internet and it will activate.
Step 7: Use Windows Firewall or Any firewall to prevent that specific .exe file to connect to the internet.
Step 8: Request refund on steam and select that the game doesn’t support on your system.
Steam has a no question asked instant refund policy if you don’t play the game for more than 2 hours.
This trick works only with Single-player games where you don’t have to sign-in to any other platform (like Rockstar games etc. won’t work because they make you sign-in to Rockstar Social)
Have fun. It works, Here’s the proof given by anonymous (Step by Step for one game)