Idk much about programming, but nene making her first game a multiplayer with controller support without prior knowledge to programing kinda amazing isn't it? At least it was more than the early access standard.

It looks like local multiplayer, so it's not as difficult as network multiplayer. There'll usually be tools that do most of the hard work of talking to the specific controllers for you, so you "just" need to map particular controllers (and their buttons) to the respective actions of each player character. It's a lot like if the game was using "W/A/S/D/L Ctrl" for player 1 and "up/left/down/right/NumPad 0" for player 2 in that sense.

It's still quite impressive to me that she has done all this in 6 months without using a game engine, using a language like C++, and while attending college for an unrelated course, though.