One first-glance problem is that your shiftValues routine needs to be a loop.
Ok so after some time working the code I now have this but still doesn't seem to be working right. Any advice on what to do next? i think maybe my gameCheck isnt what it should be but I would like some advice on what to ...

Hi. I've only recently started to learn 6502 code and decided to start off by breaking down the classic snake game found here https://skilldrick.github.io/easy6502/#snake . I'm trying to break it down into simple parts first by just making two pixels go down the assembler and then stop without any ...