Due to forgetting to set `isParticipating` of `msg.sender` to `true`, `msg.sender` can play the same game round multiple times, with their `deposits` being set to the amount of their last bet: ```solidity=126 function playWithDeposit(bool isLong, uint256 depositAmount) public { require(depositAmount >= minDepositAmount, "Wrong deposit amount"); require(!isParticipating[msg.sender], "Already participating"); require( DownPlayers.length + UpPlayers.length + 1 <= maxPlayers, "Max player amount reached" ); GameInfo memory game = decodeData(); require( game.stopPredictAt > block.timestamp && (game.totalDepositsDown + depositAmount <= type(uint32).max || game.totalDepositsUp + depositAmount <= type(uint32).max), "Game is closed for new players" ); if (isLong) { //rewrites totalDepositsUp packedData = (packedData & ~(uint256(0xFFFFFFFF) << 168)) | ((depositAmount + game.totalDepositsUp) << 168); UpPlayers.push(msg.sender); } else { //rewrites totalDepositsDown packedData = (packedData & ~(uint256(0xFFFFFFFF) << 136)) | ((depositAmount + game.totalDepositsDown) << 136); DownPlayers.push(msg.sender); } depositAmounts[msg.sender] = depositAmount; ITreasury(treasury).lock(depositAmount, msg.sender); emit UpDownNewPlayer(msg.sender, isLong, depositAmount, currentGameId); } ``` An attacker can repeatedly place small bets (e.g., 1 USDT) and then place a larger bet (e.g., 2 USDT). As a result, all of their bets will be updated to the last bet's amount (2 USDT) during the game finalization.At this point, the treasury will revert due to an underflow when it tries to distribute funds, because the funds locked in the contract for that round of the game are insufficient. This results in the `finalizeGame()` transaction failing.