pico-8 comes with a manual.txt or something
the pico-8 Wikia is very detailed
the main website's BBS has the rest, as well as a ton of examples
Trasevol_dog's patreon and twitter are a great resource as well as his games on the BBS
https://neko250.github.io/pico8-api/
https://www.lexaloffle.com/bbs/?tid=28207
they have a discord channel http://discord.gg/EwQ86eq
https://github.com/felipebueno/awesome-PICO-8
PICO-8 Shooter in 16 gifs
breakout video tutorial series
more links to tutorials
Music editor tutorial
PICO-8 Music Inspiration: Pico-8 only has 4 sound channels to work with, so if your music takes up multiple channels, that means less channels available for SFX
https://www.lexaloffle.com/bbs/?tid=4050
https://www.lexaloffle.com/bbs/?tid=28414 - very small number of tracks per song. Different music per lvl!
https://twitter.com/gruber_music - Very good musician that makes amazingly complex music with very little resources.
You can find examples of his music in games by searching for him on the BBS: https://www.lexaloffle.com/bbs/?search=gruber&cat=7
https://twitter.com/saint11 - posts tons of pixel art tutorial gifs on his patreon and consolidated here!
http://blog.studiominiboss.com/pixelart
https://twitter.com/TRASEVOL_DOG - posts a ton of graphics / effects related stuff on his patreon
Most of it is only available to patrons though so you’ll have to scrounge around the BBS for his stuff that has some of the techniques he uses. (you should be doing this whenever you see something interesting in a PICO-8 game. Look at how they did it!)
https://level0gamedev.blogspot.com/2016/05/hello-world.html - a blog by a guy that is teaching himself game dev with PICO-8
https://www.lexaloffle.com/bbs/?tid=2119 - example cog for simple map collision (note, this won’t help with things not on the map)
https://www.youtube.com/watch?v=Wj1LJQutMCY&list=PLjZAika8vyZkyOjoCp0EbHeIFZ8MLlhvg
https://twitter.com/lexaloffle/status/742449433078435840
https://twitter.com/lexaloffle/status/871048334525341697
o/
We made some tips n tricks n example carts geared toward beginners.
You might like some-a-these: https://github.com/FreeCodeCampGuam/GameDevBootcamp#gamedevbootcamp