PICO-8 seems to cost $14.99: https://www.lexaloffle.com/games.php?page=updates
Is this not open source? Are there any open source alternatives to PICO-8? The idea of PICO-8 is really good and I really liked it but I would like this to based on something open source so that I know that the platform will not disappear at the whims of the vendor and that I can hack on the platform itself if necessary.