First version of a new fantasy console/computer from Lexaloffle is available to purchase now, on sale till the end of the month.

I haven't tried it yet (other than limited messing around with the Picotron playground in the past), but am excited to check it out soon.

From their website,

Picotron is a Fantasy Workstation for making pixelart games, animations, music, demos and other curiosities. It has a toy operating system designed to be a cosy creative space, but runs on top of Windows, MacOS or Linux. Picotron apps can be made with built-in tools, and shared with other users in a special 256k png cartridge format.

Excellent video introduction by Krystian (Lazy Devs) here.

And like PICO-8, you can play anything posted to the BBS in your browser here

Short list of resources for PICO-8 development.

Introduction

What is PICO-8? (Video)

The PICO-8 Virtual Fantasy Console is an idealized constrained modern day game maker (Article)

Official

Site

Manual

Forum

Blog

Free PICO-8 version

Carts

New carts

Featured carts

Programming

Cheat sheets

Cheat Sheets by LightBWK (Image)

API Cheat Sheet by neko250 (Site)

Lua

Lua 5.2 manual

Online Lua runner

Going from Lua 5.2 to PICO-8's Lua

Code examples / libraries

PICO-ATE Altruistic Template Encyclopedia

PX9 compression

Video tutorials

Making a Shmup (Lazy Devs)

Pico-8 Tutorial Crash Course For TOTAL Game Dev Beginners! (SpaceCat)

Making an Advanced Shmup (by Lazy Devs)

Other Lists

PICO-8 Resources

Resources (by marcosecchi)

Similar projects

TIC-80

Pyxel

Please share your favorite/useful links in the comments as well!

I enjoy the limited environment, retro-like environment myself. It limits my choices to stay focused on small projects, while providing a fairly robust and modern environment to work in.