[Kaimetsu]

There are actually two, but I'm not sure if the second is applied to Graal.

The first is indeed related to movement. If x and y were locked to pixels then there'd be a limited range of movement speeds. I could move one pixel per frame, or two pixels per frame etc. To deviate from these, I'd need to code a system that keeps track of how far between pixels I am. Essentially I'd be replacing playerx with another variable, and thus negating the whole point of locking it in the first place.

The second is related to how the characters are drawn. If the game were antialiased then characters wouldn't be drawn at the nearest pixel, and thus non-pixel player coordinates would be valid.