Thanks for playing. The graphics are not made by me, but from CanariGames. I did not put much effort as I wanted to into this game, so there are a lot of undone things. I wanted to create my own graphics, but started with something pre-made just to get me started.
The secret is to figure out how you can obtain the secret shard hidden in the game. For instance, if you are able to kill the enemy in level 1, you get a pink shard in the top left corner. The secret mission is a little different in each level.
I got stuck in one of the boxes when I teleported to the shard. If I may suggest something, I would check the colliders onTriggerEnter, if that's a thing in 3d (By making a separate collider) and if something's in it then teleport it out, so I can't glitch in.