Making 4D Sokoban somewhat playable

I was watching CodeParade's video on 4D Golf when something clicked - hey, I have a 4D game too!

4D Sokoban and most 4D games have the same problem: most objects lie outside the visible slice, making them completely invisible even if they are very near. CodeParade solves this ingeniously by drawing these as "ghost" objects, "thickening" the player's view slice. I've now shamelessly copied this for 4D Sokoban, and I'm pretty happy with the result: it's instantly much more playable. Since I was touching the code, I decided to add some simple animations, giving it the wonky shifty look typical of 4D games. I won't be polishing it any further, since the game is still pretty bad (as any other sokoban without a global view); for an actually playable version, check out the original by Beekie and by Tillman.