I’m late to this thread, but, if you want a challenge, here’s an idea…

Make two simple games… like, maybe Pong and Asteroids, but, set it up so that the player can swap between the two games at will (maybe by pressing the TAB key, for example). However, both games should still be actively running even when not actively being played. Maybe, for fairness and an additional challenge, if one of the games isn’t actively being played, it still updates, but the updates are at half speed.

Is this a solid game idea? Probably not… but it would be a fun challenge to see if it can be pulled off smoothly.

Make a dice roller game/app.

Make a game where there is a countdown and you have to stop it as close to 0 as possible. Something like this Mario Party minigame: https://www.youtube.com/watch?v=hoNduqVEdTU

For extra fun, make it so the display says ??? and the player has to count the remaining time himself. The duration can also be randomized, sometimes 5 seconds, sometimes 3, sometimes 12. Good luck.

Make a physics based dice rolling app for a role playing game that rolls any number of polyhedral dice in a virtual dice tray, and provides the sum total of the roll at the bottom.

Make it so it runs on a phone, and you can roll the dice by shaking the device.

If you want something in 3D space:

1. Make a character in an open area, you can walk and jump

2. Create platforms you can jump on

3. Make a coin/sphere/mass on top of one of the platforms

4. Make it so if you touch the coin, you see a “you win!” Message or similar

5. Put multiple coins and have a counter for each collected

I did something like this in UE4 as a beginner, hoping it’s not too different in godot. Put a 60 second timer on this and you have yourself a mini game!