The email announcing this game had a link for people who already owned the original version to buy it at a discount but the link seems to be broken.
Viewing post in Serpentes: 10th Anniversary Edition 🐍 comments
We're very sorry about the mistake. Benjamin will send you a new message with the correct link as soon as Itch lets him (there's a 24h limitation) but you can correct the link yourself by changing what's before the last slash with "https://punkcake.itch.io"