@miles @whitequark That was my first guess too - a series of challenges specifically designed to be solved on an FPGA.
I'd actually been thinking it would be great to have some sort of series of challenges / puzzles for Amaranth: I'm at the stage of my learning where I can make a jiggly waveform in the (fantastic!) playground, but not yet do anything useful enough to be worth going through the pain of making stuff work on real hardware. I'm currently lacking motivation to bridge that gap.