See the original project and forum thread ( https://scratch.mit.edu/discuss/topic/125942/ ) for more info on the language Back when Stack was first made I wrote an interactive story to run in it (see the "Arctenik's programs" sprite for a copy of that), and recently I wanted that story to be conveniently runnable, so when I found that Stack didn't work in Scratch 3 I decided to edit it so that it would :-P
Most of the scripts are the same as in the original Stack 1.1, made by @BookOwl in 2015. I updated it to remove hacked blocks and created a new interface. The known differences in language behavior are: - Extension names are now case-insensitive - My cellular automaton program works in this version but not the original. I think there may be a bug in the mapping API used for variables in the original version, which might be the cause
