That time I hacked a Game Boy game

A long, long time ago, 14 years to be precise, while I was still studying in University, I was bored at home and looking for something to play. Something must have made me a bit nostalgic, and I started looking for games I played as a child. If you were alive at the time of the original Game Boy, you might remember these bootleg 32-in-1 cartridges that actually only contained a few games repeated with many names. In the one I got, there was a Hugo game that I really liked, in which you had to go through 28 levels and a final boss fight level, collecting keys to leave each level while avoiding or killing enemies, in a sort of puzzle-platformer-action game, with really simple mechanics but very fun to play.

Ever since I started playing games I've been interested in one way or another in tinkering with them. I designed levels for fictional games in notebooks when I was little, and when I discovered that some games like Age of Empires included level editors I spent hours trying them out and making levels in them. Imagine my happiness when I discovered that people made level editors for oldschool console games, my childhood games. In the end, this interest in level editing got me into programming, and by the time I played Hugo again at 20 years old, with enough programming knowledge to make some simple games around that time, I started wondering how hard would it be to actually edit that game, or make something to edit it.

I downloaded a hex editor and a Game Boy graphics viewer, and started looking. It wasn't too long after that I started noticing some regularity in big chunks of bytes, and by comparing them with the actual game reached the conclusion that those were the levels. By tinkering and comparing I eventually reached the point where I had completely deciphered the pretty simple level format the game used, and I could technically start editing levels if I wanted to.

The problem is that I didn't really know what to actually do. I'm not creative in that particular way, so I didn't really have the drive to really edit the levels, but rather to see if I could. Before I started looking into any of this, I looked to see if there were any editors for the game. There was none, and that was what fueled it all, so the most obvious next step was to make a level editor myself, right?

Writing a level editor for a Game Boy game

Of course I started writing a level editor. I am exactly the type of person who obsesses over something like this. I am also the kind of person who loses motivation quickly, so I reached out to somebody I found that made