I and my daughter made some bird sprites in PICO-8 quite some time ago, and only now have I got around to posting them to the PICO-8 BBS. Here is the link to the post with the details, along with the cartridge for you to download and use in your own PICO-8 creations:
What is PICO-8?
From the website:
PICO-8 is a fantasy console for making, sharing and playing tiny games and other computer programs. When you turn it on, the machine greets you with a commandline and simple built-in tools for creating your own cartridges and exploring the PICO-8 cartverse.
128×128 16 colours
4 channel chip blerps
256 8×8 sprites
The harsh limitations of PICO-8 are carefully chosen to be fun to work with, to encourage small but expressive designs, and to give cartridges made with PICO-8 their own particular look and feel.
PICO-8 has tools for editing code, music, sound, sprites, maps built right into the console. Create a whole game or program in one sitting without needing to leave the cosy development environment!
PICO-8 cartridges can be saved in a special .png format and sent directly to other users, shared with anyone via a web cart player, or exported to stand-alone HTML5, Windows, Mac and Linux apps.
Any cartridge can be opened again in PICO-8, letting you peek inside to modify or study the code, graphics and sound.
Explore the Cartverse
PICO-8 comes with a built-in cartridge browser called SPLORE, for searching and favouriting carts from the online collection.