As a long time HxD user, I had no idea that it had process memory editing capabilities.

It also has an xor view through feature which was very useful to me in the past. I've experienced files that use it as a simple protection.

As a kid, my eyes were opened to this stuff by wotsit.org - when I realised I could start decoding the internals of my games!

So true! That was my introduction to binary format and serialization as a kid, probably didn't even knew what these words were back then. Or, when something crashed I think there used to be button -- "Debug" an it would open up Visual/Windows Debugger with assembly filling up the screen.

As a kids I used to edit mIRC's ctcp version reply with an hex editor.... Probably 25 years ago

Yeah. I learned in primary school that I could bypass a password prompt in a simple program just by changing one conditional jump instruction to another (if password is wrong, success)

I just installed ImHex, and I saw an option to attach to a GDB server. I assume that implies memory editing capabilities, but I haven't tried it yet.

I also don't know how the situation would be on non-GNU platforms, although I think GDB is a thing on Windows with MinGW?