The Fat Bird Game by MushroomDev is a 2D endless platformer game made for the Nintendo Game Boy.
In this game, you play as a bird but you can’t fly. You have to walk and position yourself to drop down in the abyss, while avoiding the spikes and the big lurking rats. You can collect apples and earn points. Some apples are magical that walk, so you have to be careful while collecting them. They move fast and you might tangle your legs in the spikes, which basically turns into a game over. There are teleporters as well, which you can use.