I was sincerely considering picking it up, but it actually surprised the shit out of me to find that it had a license cost.
I’d rather just dev for a SEGA genesis or equivalent and have the benefit of running it on real hardware. There’s certainly a fantastic, enormous and open-source-focused world and community behind that.
I'm all for homebrew dev on classic consoles (Mega Drive being my favourite also) yet these fantasy consoles are much easier to program for and usually have more meaningful constraints targeted towards finishing little projects while going solo.
Check out this list of free pico-8 clones, some of which support programming in lisp like languages even:
My thought process though that Pico-8 is roughly the same price as three cups of coffee. However, it is a way to say Thank you, Zep and support the future development of the platform. Some interesting things came out of Pico-8 BBS and also helped me to sharpen my skills.
If it is too much or inconvenient there is also TIC-80 which is open-source and more-or-less follows the same spirit albeit less constrictive.
Pico-8 is absolutely worth $15 IMO, and the creator more than deserves the asking price.