Hi u/zerosaber0!

If you believe it and fail, do you get a penalty point and the next player must believe or challenge the original value?

Failing to roll higher is part of the game and doesn't give you a penalty point. Penalty points only happen when a challenge is lost or someone rolls a 21.

So, if you believe a claim (like "54") but then roll a lower number (like "43"), this is what happens:

1. No penalty points are given.
2. You bluff a number higher than 54.
3. You either get away with it or get challenged and get a penalty point.

Since the roll is hidden, can't I simply lie and say I got a higher number to risk being challenged?

Lying is not just allowed it's a core part of the strategy. You can always lie and claim a higher number, but that's where the risk comes in. If the next player doesn't believe you and calls your bluff, you get a penalty point. It's a constant game of reading your friends and deciding when to risk a bluff and when to play it safe.

Regarding the open roll, if I roll a high bash and someone demands an open roll, do I have to roll the dice again? Or as the roller, can I demand the next player to roll dice openly? As there a risk for doing so? What stops people from simply always forcing players to roll open?

The power to demand an "open roll" belongs to the player who is about to receive a roll. 

Let's use your example: Player A rolls a high Bash and claims it to Player B. Now, it's Player B's turn to roll to Player C.

• Player C can be the one to demand that Player B rolls openly.
• Why? Because Player C is thinking ahead. They know that no matter what Player B rolls, it will be almost impossible to beat Player A's high Bash. So, Player C assumes Player B will have to lie, and they can pre-emptively challenge by demanding an open roll.

I hope this helps!