>>3163622Your picrelated was done by just one anon but with the GameMaker engine, if I'm right, and for iiCantra it was written specially and rewritten more then once with a few different people, and other people made the art (maybe more than one, I don't sure) and the music, and game- and level- design .
Also, right now there is
https://iichan.hk/b/res/4601587.html where OP making his own simple mario-clone.