Root + Impact

Description

• The claimFee is designed to increase by a fixed percentage (feeIncreasePercentage) after each successful throne claim to incentivize progressively higher stakes.

• However, when the initial claimFee is set to a very small value (e.g., below 100 / feeIncreasePercentage wei), the calculated fee increment (claimFee * feeIncreasePercentage) / 100 evaluates to zero due to integer division rounding.

• As a result, the claimFee remains constant across claims, breaking the intended progressive increase mechanic.

Risk

Likelihood:

• This issue only manifests if the initial claimFee is configured with a very small value, which is unlikely under typical deployment parameters.

Impact:

• The stagnation of the claimFee breaks the game's economic design by allowing players to claim the throne repeatedly at a fixed minimal cost, potentially impacting user incentives and gameplay fairness.

Proof of Concept

Deploy the contract with an initial claimFee of 1 wei and a feeIncreasePercentage of 10.

After a player successfully calls claimThrone() by sending 1 wei, observe that the claimFee remains 1 wei due to rounding of the increment to zero.

Recommended Mitigation

Implement a minimum increment logic to guarantee the claimFee increases by at least 1 wei per claim:

Alternatively, enforce a reasonable lower bound on the initial claimFee during contract deployment to prevent values that would cause zero increments.