@lmerckx Thank you for the answer but that was not the point of my first question: although PICO-8 cartridges are free, the PICO-8 runtime requires a paid license if you want to run it on linux/windows/rpi (the browser version is free). The PICO-8 machine is not open-source and if you need a binary/executable for a RPi, you can't build it yourself, you need to buy it first before you can download it. So my question is: how can the PICO-8 runtime be redistributed with Recalbox without paying for it? Is that legal? I was thinking that Recalbox could be made to work with PICO-8 as long as the PICO-8 machine was downloaded/installed by the user... but seeing that it's not required to provide the PICO-8 executable, I am questioning the legality of its inclusion in RB.
Concerning games, I was specifically asking about the ones which do not fit on a single cartridge (and often use external lua scripts) like poom and ufo.