A bit of trivia:
Some people fail to realise that on an XBox controller (any gen) you can press the A button halfway and still have it register (if the game can sense pressure). I believe you can do that on newer Nintendo consoles as well. However, Sony consoles don’t have an A button: they do have Triangle, Square, Circle, and Cross, though. Half Cross/Circle would be the equivalent on PS2, PS3, and PS4 (as of this writing).

This means modern consoles can do actual half presses on any button (except maybe the D-pad), not just the “hold before level start” kind of half press Pannenkoek talks about in his video (you know which one I’m talking about). PC keyboards are NOT pressure sensitive, so for PC games, you will need a pressure sensitive controller peripheral to do the kind of half press where you only press the button down halfway. You can still do the “hold before level start” half press on a keyboard, though.