It's called Bitsy, and it basically lets you make a little world where the player can walk around and talk to things. It's very limited but it's also VERY easy to use and you can get some fun stuff going with it.
Check it out here: https://ledoux.itch.io/bitsy
I've made a few games which I'm going to link below. I've also played some really cool games that use the engine; I'll try to find those again and link them in here later... but yeah, bitsy. It's cool. Share stuff in this thread if you make anything or know of any cool bitsy games!
GAMES I MADE: