Files with hpa suffix can be found as archives made using Hyper Patcher 2 software.
HPA file extension - Hyper Patch archive
What is hpa file? How to open hpa files?
File type specification:
File extension hpa seems to be mainly used for a special archive format created and used by Hyper Patcher 2 program. Possibly a little outdated format that may not be well supported in other programs.