The image above is a screenshot of a folder on my computer. The pictures were extracted from Fossil Fighters using FFTool, so thanks to jianmingyong for making that.
Internally, this game is an absolute mess. It uses custom formats for everything, including twice-compressed archives inside of containers. Every vivosaur in every team gets its own AI file (give or take), and every move individually defines status variables (e.g. how much damage poison deals), despite the fact that only two different amounts get used (Normal and Gold). There are unused moves and unused areas, including an entire Beta Vivosaur Island (upon which, fun fact, the Rosie night-time "date" cutscene is set). The file named "japanese" contains the English text strings, and the file named "english" contains the Japanese ones. And I could go on.
But really, what takes the cake are the lifebars. In a normal game, you'd have one sprite for each type's lifebar border, one sprite for the empty inner bar, and then a defined color or two to fill it in with proportionately. Not Fossil Fighters though! There are 779 different lifebar sprites, one for every single combination of border, health color, and health amount. In fact, if you use memory editing to make a vivosaur's HP more than a little beyond their maximum, the game outright crashes, not because it can't handle the idea, but because it doesn't have a sprite for that. God I love this game.