Maybe you could argue their moral right to the artistic integrity of the work was violated, but that seems like it would be a rather uphill battle. In a modern context if DRM was involved, maybe the anticircumvention would come into play.
IANAL
The thing is, 30 years ago a Game Genie was just a way to get some fun out of old cartridges, or blast through an unfair game. Nowadays most games have some kind of an online component, if they're not entirely multiplayer. Hell, most players of online multiplayer games would love to see the cheaters plaguing their games go to jail. Effectively, not only have the conditions of the market changed so much as to render the Galoob precedent unusable, it also makes it kind of anti-consumer, at least in the context of online multiplayer.
Microtransactions also ruin the Galoob precedent - obviously if people are selling you what are effectively cheats, then your cheat device is usurping the market. I bet you if Nintendo had found a way to charge you a quarter every time Mario lost a life, the court would have ruled the other way.
(Blizzard is also responsible for using the DMCA to ban server emulators, see https://en.wikipedia.org/wiki/Bnetd#Blizzard_takedown_demand... . They argued that a server emulator that doesn't check CD Keys is a circumvention tool, and won. Hell, I'm pretty sure this is THE reason why the DMCA exception for old game servers explicitly only covers situations in which the developer released an authorized server program, such as Valve games or Java Minecraft.)
If I modify my honda civic with a body kit I'm breaking IP?
If I put a sticker over the apple logo on my MBP I'm infringing on their design?
to me the modification of bits in MY Nintendo from MY Cartridge should be none of their business.
The things you describe are legitimately derivative works in the scope of copyright's worldview.
The issue is that viewing every single idea or concept as "property" with an owner and a price tag attached is a fundamentally broken model.
My original point about the idea that someone can own a song or a number as if it were property is fundamentally insane.
The fact that it being a violation or not depending upon whether the song is sung in public or in private illustrates that point nicely.
With multiplayer games cheating is definitely a TOS violation but again not copyright infringement.