I just came across Pico-8, did a few tutorials last weekend, and here's my first cart-- a spaceship flying over an endless 2D parallax scrolling background (with more layers that get added in over time).
The whole experience was a lot of fun for someone who rarely writes software-- just poking around within the tool and trying things out. Thank you to everyone who developed Pico-8 and posted tutorials and tips!
I didn't plan to share anything because this isn't a "game" and I expect the code has all sorts of ugly parts I should clean up. But I saw a talk about how part of the concept is just encouraging sharing in any form. So why not... feedback welcome.
p.s. thanks to @Gruber for the music shared in the Pico-8 Tunes #1 cart.