Keep in mind when making a hitbox you will probably have to handle SOCD (simultaneous opposing cardinal directions), many games don't handle up+down or left+right in a sensible way, the exception to this being if you're using a Cthulhu PCB and not any other PCB with your hitbox, as the Cthulhu has a built-in filter.
You can use two 7400 logic chips to do it or assemble a SOCD filter from godlikecontrols.com
This is only tangentially-related, but I always wanted to make a Saturn/Dreamcast/PS2-compatible homebrew twinstick setup for Virtual On. Has anyone figured out a logic diagram (with 7400s or something, although a microcontroller may be simpler in this case...) where you have two sticks, two trigger buttons (weapons) and two thumb buttons (dash)
move forward
move back
move right
move left
rotate right
rotate left
jump
block
weapon "A"
weapon "B"
+ weapon "C"
or + or or or dash
ect...
I can probably figure it out on my own, but I hate duplication of labor. I just want to know if anyone has done it.