Do you want to sort OpenCart according to category sort order? This video will show you how to achieve it by hard coding the core file.
This tutorial is only for OpenCart version 22.214.171.124 and it should also work in version 126.96.36.199. It might also work in latest version v188.8.131.52. I have not tested this on v2 but if the core script are the same, it will work in v2 as well.
Link to this video at https://www.youtube.com/embed/UW-YrwRpVqA.
Previously this blog known as cozomi.com