system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do Japanese side-scrollers move from left to right when Japanese text is read right to left?

I assume it may have something to do with western predecessors?
gpt
It has nothing to do with western games at all.

Vertical Japanese is read top-down from columns on the right side of the page to the left. 

However, horizontal Japanese is read left to right from top to bottom, akin to most western writing. 

Vertical movement in games is harder than horizontal (in terms of gameplay), so horizontal was used and left-right became the norm.