Root + Impact

Root Cause

The root cause is a simple logical error in the claimThrone function's validation logic. The code incorrectly uses the equality operator (==) instead of the inequality operator (!=) in the following line:

require(msg.sender == currentKing, ...)

This condition makes it impossible for any new player to enter the game.

Impact

This bug leads to a complete Denial of Service (DoS) for the entire protocol.

Since the claimThrone function is the main entry point to the game and is non-functional, no player can participate. As a result, the protocol is entirely unusable and frozen from the moment of deployment, preventing it from generating any value.

Description

• The claimThrone function contains a critical logic error in its validation check. It incorrectly requires a new player to already be the king. This fundamental flaw blocks all new players from entering, making the entire game unplayable.

  
  

Risk

Likelihood:

• Reason 1: A new user, who is not the current king, calls the claimThrone function to participate in the game.

• Reason 2: The function's validation logic executes the flawed access control check, which will fail for any new user.

Impact:

• Impact 1: The core gameplay function, claimThrone, is permanently non-functional for all new players.

• Impact 2: The entire game protocol is unusable (Denial of Service), as no one can participate after deployment.

Proof of Concept

Expected Output

Recommended Mitigation

The validation logic within the claimThrone function must be corrected to ensure a new player is not the currentKing. This is achieved by changing the equality operator (==) to an inequality operator (!=) as shown below.