This is a fun little coding practice game, that's all about understanding code line by line. You send the baackend url and room name to one of your friends and start battling it out. It has no syntax highlighting, or any other comforts present in a regular ide, meaning it can reveal your true knowledge of the language. Talking about languages, this app can facilitate EVERY one that uses an ASCII characterset. (it might be unicode, but I am not sure and will not check)

You get together with someone and send them the website link and the backend link, usually the same.
You both connect to the same room and the coder starts writing their code..
Once done, they submit their line and the compiler interprets it..
Once ok, the compiler clicks understood and the coder can continue..
If the coder is finished, they can click the finish button to review the code..