Add sub-frame inputs
Allow doing multiple inputs of the same key during a single frame.
Would you mind elaborating on sub frame input? I never really understood what it does.
Maybe it is a bad description of it but in some games you can give multiple inputs of the same key during one frame. For instance in some strategy games you can perform multiple commands during a frame and they all get processed after the frame has passed.
A good example would be DOS - in jpc-rr, you can press and release a key as many times as you want, and advance time any number of milliseconds you like. The keyboard inputs get placed in a buffer, and the game processes them as fast as it can - depending on the game, it might care about inputs only once per frame, or it might honour every single input it sees. It makes sense that some PC games would do this too.