Celeste, which was released to rave reviews this past year for the Switch, started life as a PICO-8 game. I played it on the PICO-8 at first and was blown away!
PICO-8 (and I assume, TIC-80 as well) are actually great for prototyping bigger game development projects - specifically due to its harsh constraints, which force a limited scope and sharp focus on the design.
I'm actually in the process of making SlipWays, a fast-paced 4X game for PC that started as a PICO-8 prototype (https://krajzeg.itch.io/slipways). A major reason for the tight game design of the game were the tight confines on the console.
I love SlipWays! It's really impressive that you crammed a game that deep into such a small system. That and Celeste were big inspirations to look into PICO-8 myself. Looking forward to the full release.
One of the coolest hidden easter eggs in the main release of Celeste is stumbling upon the little room with the PICO-8 version of the game (https://i.imgur.com/7iNbBNA.png). I didn't know PICO-8 was a thing, so imagine my surprise when I found an entire complete game built into the main game!
The commercial release of Celeste is a new game, written from scratch, implemented in C# (XNA/FNA/MonoGame). It includes a port of the original. I'm kind of curious if they actually wrote a PICO-8 emulator for that or just ported it to C#.
I'm actually in the process of making SlipWays, a fast-paced 4X game for PC that started as a PICO-8 prototype (https://krajzeg.itch.io/slipways). A major reason for the tight game design of the game were the tight confines on the console.