This is not made in PICO-8.
I tagged it because it uses the PICO-8 colour palette, even though it is not made with PICO-8. A few people have been confused about this in the past ^^
Now that I'm looking at the game's metadata, I see PICO-8 is also somehow listed in the "Made with" category, which is definitely a mistake, I'll see if I can at least fix that.