This one was quite well made. Even though these types of games are not my cup of tea I almost managed to finish the first level 😃
I feel like a lot of the difficulty comes from not the actual physics puzzle, but the (intentionally?) obtuse controls. I feel like if there were a setting for swapping the force curve (the closer to the dice, the lower the force), it would make it a lot more enjoyable. Currently a single pixel difference in the mouse positioning makes a huge difference in trajectory, and it so it is very hard to change direction mid-flight.
Also, as others have mentioned, you can just revert to a 6 when you land. The player has the option of doing so with extremely small steps, and there is no disadvantage to doing so. The only place I see this making a difference is if the player lands on a 1 on a slanted platform. Maybe you could make it so that after a second or so the number goes back to 6?
I liked how colliding with a wall makes you unable to control the dice though. It led to some tense moments where I knew I was at the mercy of the physics engine. 😆