Horizon Zero Dawn Original PS4 Version Rises in Price to $39.99, Closing the Affordable Upgrade Remaster Channel.

Upon the unveiling of Horizon Zero Dawn Remastered for PS5/PC, Sony has hiked the price of the original Horizon Zero Dawn version for PS4 from $19.99 to $39.99 with no apparent reason (price in Thai stores is 1,290 baht). IGN speculates that the reason behind this is due to the fact that Horizon Zero Dawn Remastered is priced at $49.99, but if you already own the original Horizon Zero Dawn, you can upgrade for $9.99. The original PS4 game is being sold for $19.99. Therefore, it is more cost-effective to purchase Horizon Zero Dawn Remastered for $19.99 + upgrade for $9.99 than buying the full game. Consequently, Sony had to raise the price of the original game to make the upgrade cost equitable. Source: IGN

TLDR: Sony increased the price of the original Horizon Zero Dawn game following the introduction of Horizon Zero Dawn Remastered, speculated to align the upgrade cost.