TL;DR:

• Invasion project (a shmup game for PICO-8) unlocks after you complete Shape language.

• Customize the Invasion design document on the Pixeltosh.

• Chronoscope, a magazine with science fiction artworks for inspiration and reference.

• A new dynamic soundtrack song plays in Pixel art fundamentals and Invasion project.

After a bunch of theory around designing shapes, it's time to put things into practice by drawing sprites for a simple, single-screen shoot em' up.

It runs on PICO-8, so it's not a long project like the Pinball game, but it's not as simple as the Snake game either. The extra bit of functionality is that you have the chance to customize the design document for the game.

You can change every underlined word in the document …

… and adjust plenty of numeric properties.

The main thing is of course still to draw the sprites.

And you have a new magazine/book available if you choose to design your game with the science fiction theme.

Of course you get to play the game and tweak it until you're happy with the gameplay.

There was also a new song added to the game's OST (you can hear it when you don't have a cassette tape playing in the Music app) and I'm so happy with how it turned out. It appears at the end of the devlog as well:

I hope you will have fun coming up with creative ways to change the design. I can make it even more advanced in the future (multiple sprites for invaders, invaders that attack out of formation, rotating and animated sprites) as right now it's still quite limited, but of course there's a million other things to develop too, so I'll get back to new tutorials next.

Cheers!
—Retro