[yori]

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.

[tunaoftheland]

One that I've kicked around with is TIC-80: https://github.com/nesbox/TIC-80

A bit more generous with the system resources, but PICO-8 does have a bigger community and "carts" to download and poke around with.

[makapuf]

You can have a look there: https://github.com/paladin-t/fantasy

[JoshTriplett]

There are multiple Open Source implementations of the PICO-8 "console", such as https://github.com/Gigoteur/UnicornConsole (formerly "PX8").