Because he's working on the full steam release you won't be able to buy the game again on this site. You van buy it from the 22nd of July from here: http://store.steampowered.com/app/477160 . If you already bought it you can still use your private download link to get the game.
If you already bought it, and you added it to your collection you get a download button on the top of your screen, else you can still use the download link. The buy link is deleted, and you can buy it after 21st of July on the Steam page.