Sony has blocked the purchase of Horizon Zero Dawn ahead of the release of the remaster

If you were previously able to purchase Horizon Zero Dawn on PC, it’s worth checking again – the game may now be unavailable to you. Due to the upcoming release of Horizon Zero Dawn Remastered, Sony has removed the original version from sale to millions of players in over 170 countries.
Sony has now removed the original version from sale to millions of players in over 170 countries.
PSN account requirement
A PlayStation Network account will now be required to purchase the remaster, something that wasn’t required in the 2020 version. As users on the ResetEra forum have noticed, Sony has removed the ability to buy Horizon Zero Dawn on Steam and the Epic Games Store in preparation for the remaster’s October 31 release. While the game’s Steam page still exists, the “Add to Cart” button is no longer there. So to play Horizon Zero Dawn on PC, you’ll need to pre-purchase the remaster, unless of course you already own the old version.
Horizon Zero Dawn is now available on Steam.

The remaster adds improvements such as rewritten dialog and updated animations, but the key change is the mandatory PSN requirement.
Access restrictions for multiple countries
The problem is that PSN is only officially available in a limited number of countries, making the remaster unavailable for purchase in over 170 countries. This same situation occurred with God of War Ragnarok and Ghost of Tsushima Director’s Cut, as well as Helldivers 2, when the PSN mandatory requirement was introduced weeks after the game’s release, prompting negative reactions and critical acclaim from users.
Another problem is that the PSN is only officially available in a limited number of countries, making the remaster unavailable for purchase in 170 countries around the world.