Personalized Copies?
To you, "personalized copies" may sound like a myth, and in many ways you're right.
But, I have seen some strange things in games that i can't find online. Here is a list of some of them.
Super Mario Land 2: For some reason, whenever you put the game in a original Gameboy, it erases the saves.
But, when you put it in a Gameboy Advance, it works perfectly. Maybe it's something with the battery but idk.
Donkey Kong Land: It has some weird graphical glitches. The sprites appear to be disintergrating? Possibly caused by dirty contacts.
Punchout!: Kinda simular to DKL but, it doesn't begin until a few fights in. I keep cleaning it, but it comes back.
Rad Racer 2: One of weirdest enounters i've experienced, the graphical glitches keep appearing in the exact same way EVERY TIME.
No matter how much I clean the contacts, it always glitches in the EXACT SAME WAY.
It doesn't begin until you start the race. It glitches it to look like the sky is the ground and there are random numbers at the very top of the sky.
The gameplay isn't any different, just a little harder due to the screwed up graphics.
Pro Pool (GBC): There is a song in the game that always play when you play pool. But, i can't find it anywhere online.
There are few youtube videos for the game itself, but even then i look at a lot of them, and the song is replaced by a different one.
I made a very bad recording Here.
