Last Man Standing
First Flight #45
Beginner FriendlyFoundrySolidity
100 EXP
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Submission Details
Severity: medium
Valid

Previous King Payout Missing

ishwar

Description

  • In the intended game design, when a player claims the throne, a portion of their claim fee should be paid to the previous king. This incentivizes participation and rewards dethroned kings.

  • However, the code does not implement this mechanic. The variable previousKingPayout is defined but never assigned or used, resulting in no payout for dethroned kings.

function claimThrone() external payable gameNotEnded nonReentrant {
// ...snip...
uint256 previousKingPayout = 0; // <-- always zero, never assigned
// ...snip...
// Defensive check to ensure platformFee doesn't exceed available amount after previousKingPayout
if (currentPlatformFee > (sentAmount - previousKingPayout)) {
currentPlatformFee = sentAmount - previousKingPayout;
}
platformFeesBalance = platformFeesBalance + currentPlatformFee;
​
// Remaining amount goes to the pot
amountToPot = sentAmount - currentPlatformFee;
pot = pot + amountToPot;
// ...snip...
}

Risk

Likelihood:

  • This will occur every time a new player claims the throne after the initial round.

  • No dethroned king will ever receive their intended payout.

Impact:

  • Dethroned kings have no financial incentive to participate further.

  • The absence of this reward undermines engagement, game fairness, and retention.

Proof of Concept

// previousKingPayout is always zero, no transfer to previous king
uint256 previousKingPayout = 0; // <-- always zero, never assigned

Explanation:
The payout logic is missing. Even though the variable exists, it is never set to a meaningful value nor used to update balances for the previous king. The code thus breaks a fundamental incentive of the game.

Recommended Mitigation

- uint256 previousKingPayout = 0;
+ uint256 previousKingPayout = (sentAmount * previousKingPercentage) / 100;
+ if (currentKing != address(0)) {
+ pendingWinnings[currentKing] += previousKingPayout;
+ }

Mitigation Explanation:
Add a configurable percentage (previousKingPercentage) and update the previous king's pending winnings. This restores the intended payout mechanic and aligns incentives with the game’s design.

Updates

Appeal created

inallhonesty Lead Judge about 2 months ago
Submission Judgement Published
Validated
Assigned finding tags:

Missing Previous King Payout Functionality

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