Ask HN: Program ideas to write in Assembly – to feel like a Wizard?

I've been following the NandToTetris course and am fascinated by the low level programming parts, especially the Assembly language parts.

I already know 3 high-level languages, and C.

What kind of programs can I write in ARM assembly:

- Where Assembly is the "right" choice?

- The program is super fun to reason about?

- I can feel like a Wizard

- I have to think about optimisations by hand

Basically I want to play around, and think about computer architectures.

Alternatively I have a Raspberry Pi Zero, so could write on that too.