In my opinion, pico-8's musical notes don't go nearly low enough.

In addition, its UI assigns numerical values to notes' octaves which are off by 2. (A middle C in reality lies at the bottom of octave 4. In pico-8, its octave is labeled as 2)

Personally, I would love pico-8 to at least cover the range of a traditional 4-string bass guitar, down to e1. (in the 1.8 UI that note would be labeled as octave -1) Even better would be getting all the way to octave 0.

(also, I'm aware I can put a track in "slow" mode.)

I was going to say something unhelpful about there not being enough cart space for a wider pitch range, but then I remembered that notes have a presumably unused bit. Assuming that bit is actually available, it'd be a tad ugly in memory but we could conceivably use that bit to support the 7-bit MIDI note range. The octaves should probably be renumbered in the UI to match, but the data itself could be backwards compatible. Just a thought.

The limitations of pico-8 are "carefully chosen" and hopefully will give all pico-8 carts a "similar feel." My guess is that zep wanted higher pitch notes to be a staple of pico-8 carts

FYI this is an old thread but you can now use SFX instruments to reach lower octaves. There is a shortcoming (arguably a bug) which means you can't use them for syncopated rhythms where you want to hold a note across SFX boundaries, as I've detailed here, but other than that, it's a great boon to basslines :)