I found the easter egg/heart...
By Your Side
This game was made for the Lost Relic Games Game Jam, with the theme "Connection". Even though I didn't have a lot of time, I wanted to submit something, and I had the idea to make a game about friendship :^) because I'm cheesy and cringe, idk
The game is a just simple platformer, but halfway through, you meet an AI companion that will travel along with you. If it gets ahead of you, you can teleport to it by pressing Q, because uhhh the power of friendship or something like that.
The AI's movement isn't hardcoded -- it plays by the same rules as you, and everything is dynamically calculated, from its current goal (whether it wants to follow you, go to a checkpoint, etc) to its chosen path (how it'll get to the goal) to the controls it chooses on each frame (it walks, jumps, and dashes just like you). There's only about 2 places on the map that it can't traverse in both directions (though it can get all the way from where it starts to the end); otherwise, feel free to run around all over and test whether it can follow you :) [it also can die, just like you, in which case it'll use your spawn points]
The game is pretty basic, since it was just a little idea I had and wanted to test out (and it took 2-3 days to get the AI working properly in all the scenarios), but it still has fully rebindable controls. Also, there's a secret area somewhere ;)
Oh btw this game uses Kenney's Platformer Art: Pixel Redux assets (some modified).