While the game can be hard to complete itself, doing this won't be as hard as beating the actual game. You won't even need to go into the basement!

This is a guide on how to discover the secret in Dark Riddle! Assuming you've seen my guide on how to beat the game, this will be a less detailed guide as you are probably more familiar with the layout of the house by now. If you didn't read my walkthrough, I would encourage you to do so!

Now, when you load into your game, you want to jump over his gate to get inside his house. Go inside and get upstairs into the attic. In the area where the nippers and telescope are, you'll want to take the item next to the nippers, which should be a rocket part. Now, the easiest way to get into the room to put the rocket together is by jumping out the window and jump onto the right lower roof. Then to your left, you'll see two front windows. Break one of them and climb inside. Finally, on a shelf to the left side of the room will be the bottom of the rocket part. Tap the "use" button on the rocket part to put the rocket back together. When you have done it, the shelf will move out of the way! Then, tap the sun in the middle of the room to get the text "Universal Map Discovered"!

And that's all to it! I have a few theories on this and about the neighbor, like maybe he is an alien??? But that's the tutorial on how to do it! It doesn't give you anything special, but it's a cool secret to find!