As long as the ROMs are completely original homebrew games such as found at the ROM Packs and PD ROMs website, it is completely legal. These games are designed by amateurs and usually come with as a freeware or they don't have copyrights information at all.
Co: "This bug drove me insane. I tried a lot of things to debug, it just stuck".
Me: "How did you debug it?"
Co: *shows a complicated debugging method using breakpoints and everything*
Me: "What about ... " *casually prints a stack trace in the try/catch exception
Co: "Wait, you can do that??"
So after completing the Mass Effect Trilogy the first time as a Vanguard, I decided to replay the trilogy as a Soldier. Thus far, I've just finished the Horizon mission in ME2, and I'm already exhausted from ME2's f**k-awful enemy design.
I can't stop buying resource packs I'll never use, or engines for that matter, or free resources as my two terabyte external will attest. I am a digital hoarder I guess. Some people get drunk off the silly juice when they are bored, I just buy shiny digital nonsense I don't need.