This is my first game made with PICO-8 (my first game at all for maybe 20 years unless you count a few Mario Maker levels), and I've enjoyed the experience. I wanted to share here a list of resources that I found helpful including code snippets that I incorporated or adapted. Fellow PICO-8 programmers' posts were especially helpful; unless otherwise noted, most of the below links go to the Lexaloffle BBS.

The pieces and starting positions are randomized based on MBoffin's implementation of a Fisher-Yates shuffling algorithm. The sort function used was Impbox's insertion sort.

I wanted to make movements smoother so I wound up in the world of easing functions. I used some from this library via ValerADHD. From there I also found the website Easings.net to be useful! I tried making a bezier curve function using the Wikipedia page for them but that's not implemented yet.

I used Saccharine's string-padding function to add leading zeroes. I needed to convert numbers from base-10 at various points and used Felice's hex and dw817's binary conversion functions for that. This Pastebin code helped make the "typewriter text" on the title screen come to life.

Krystman's itch.io devlog for the PICO-8 game PICO Checkmate was very, very helpful and a great read, this entry on chess engine basics in particular. My game doesn't have a true opponent, so the information on chess engine algorithms was fascinating but not used in this game. The main breakthrough it gave me was in the board representation section. Before reading this, I figured I would use a two-dimensional array; the explanation immediately persuaded me to go with one dimension instead. This ended up making it very easy to implement new pieces.

Finally, many of the guides at Nerdy Teachers as well as Dylan Bennett's top-down adventure game tutorial videos were useful in getting organized and understanding the flow of a PICO-8 program.