You know Pi's drive you crazy, they don't work properly or the way you want them to, maybe just mine is possesed by the devil.
I had many experts stumped by my Pi problem, Im kind of lumped with XP and I know for a fact that not one person on this site/passing through could get my Pi working with ICS while ethernetted to my laptop.
They may be able to if they teach me to reprogram XP.
Of course you can write an N64 emulator to run on a Raspberry Pi. You could emulate the PS3 on an Amiga if you wanted to, but it would be slow as hell. There are no PS3 or XBox 360 emulators (that I'm aware of) for the PC because, on the average PC, the emulation would be far too slow, just as an N64 emulator would probably be slow on a Raspberry Pi. Just because it's physically possible doesn't mean it's practical.
[edit: This was a response to another user whose post has been deleted for some reason]
Because someone thought it would be fun to report people for no reason again.
I was wondering if dos could run on PI
Nope, MS-DOS was written entirely in x86 assembly and uses the PC BIOS. To port it to the RPi, not only would you have to convert all of the x86 assembly code to ARMv7 assembly code, you would also have to write new code to replace all the BIOS code. It would probably end up being more work than writing your own OS, and that's for a decades-old, obsolete system.
[do] you think it would be practical to edit the PI OS to make my game system OS
There is no Raspberry Pi OS. There's a modified Linux kernel and some modified Linux distributions that are available for it, but no official Raspberry Pi OS. I actually think it would be more work to learn enough about Linux to be able to modify it to your ends than it would to be to write your own basic OS. Linux consists of millions of lines of code, whereas an OS sufficient to run video games could be done in about a thousand. The easiest option would be to just write a GUI that runs on top of Linux, but where's the fun in that?