you sure becuse im pretty fucking sure this is just a pirated game which is not allowed. i will wait for the devs response
Nacho Sama is literally the dev himself and this is the old version. I'm pretty sure he makes it free because people kept demanding for refund after the Steam (remake) version released, so he eventually make this one free while the Steam version still costs money. You can read the previous devlogs if you want to see what happened last year.