I was just wondering if there was a way to make a completely new game or hack one. Please help.

You need hack tools for the game you want to hack, you can download from several pages, just looking for a bit, but not always you find what you really wanted.

This depends on what you're trying to accomplish. If all you want to do is a text hack (changing the in-game dialogue), you actually accomplish this with just a hex editor. Sometimes really simple NES games store their text in a manner that makes it show up as regular letters on the right-hand side of the hex editor so you can edit this easily. I think Mega Man 2's intro was like that.

More advanced games require you to figure out not only where in the ROM the text is located, but what hex value each letter equals. Once you've accomplished the latter, you'll want to create a table that tells these values to the hex editor. Doing this will make the right-hand side display the text as regular letters so you can edit more easily.

If you want to do a palette swap, this can usually be done in a hex editor as well, particularly for NES games. If you can figure out which part of the game data tells the sprite what colors of the game's palette to use, you can alter these values to re-assign the colors.

If you want to actually change the pixels of the graphics, you're gonna want something more advanced like a Tile Editor.

Changing the palettes available for use in the ROM can also be difficult. I only know how to do this for GBA games with Advanced Palette Editor.

Certain games are so huge that they have a wide array of hacking tools JUST for that game. If you're lucky enough to be hacking one of those, then you can find lots of resources and support. Examples of this would be most Pokemon games, Mario, and some Mega Man games.

I want to try to do this too, but is it legal? I thought I heard that it isn't actually legal to make your own game, but I don't really understand what those people mean when they say that, because they say something about backups when they say it.

Local Mods: You can close this. I already got my answer.