sorry for the lateness of answer.
we are so late to investigate accurately

below is to call bitcoin transaction.

gettransaction 14da22d733133a0c978cad711f67d2a22d16117f1635422385e3e83743f54b0a
{
    "amount" : 0.01000000,
    "confirmations" : 154,
    "blockhash" : "0000000000000000032dc03d03b7695a38967619876c6616bbfe306c6b4ac17f",
    "blockindex" : 658,
    "blocktime" : 1413871005,
    "txid" : "14da22d733133a0c978cad711f67d2a22d16117f1635422385e3e83743f54b0a",
    "walletconflicts" : [
    ],
   "time" : 1413870197,  ==> 05:43:17(GMT)
    "timereceived" : 1413870197,
    "details" : [
        {
            "address" : "1AbqpCSYzummeuMSrVsXVNjqf9kxkitt1Q",
            "category" : "receive",
            "amount" : 0.01000000
        }

"time" : 1413870197  is time that transaction is generated.
if this time convert to  GMT  , GMT is  05:43:17.

transaction generation time is 05:43:17(GMT)
your game starts at S:05:43:18(GMT) .

so, our system has no problem.
but Time of https://blockchain.info about this transaction is strange.

if you compare to the other site, you will know what i am say is right.
only blockchain.info has been displayed different time.

https://blockchain.info/tx/14da22d733133a0c978cad711f67d2a22d16117f1635422385e3e83743f54b0a
https://www.biteasy.com/blockchain/transactions/14da22d733133a0c978cad711f67d2a22d16117f1635422385e3e83743f54b0a
https://www.blocktrail.com/BTC/tx/14da22d733133a0c978cad711f67d2a22d16117f1635422385e3e83743f54b0a

below transaction is the same.
---------------------------------------------------------------------------------------------------------------------
gettransaction 2b3a6b69175251825a779bf928345a4a4525588078cdbc26abe49b35c4253505
{
    "amount" : 0.01000000,
    "confirmations" : 158,
    "blockhash" : "0000000000000000032dc03d03b7695a38967619876c6616bbfe306c6b4ac17f",
    "blockindex" : 659,
    "blocktime" : 1413871005,
    "txid" : "2b3a6b69175251825a779bf928345a4a4525588078cdbc26abe49b35c4253505",
    "walletconflicts" : [
    ],
   "time" : 1413870227,   ==> 05:43:47(GMT)
    "timereceived" : 1413870227,
    "details" : [
        {
            "account" : "EURUSD_D",
            "address" : "1AbqpCSYzummeuMSrVsXVNjqf9kxkitt1Q",
            "category" : "receive",
            "amount" : 0.01000000
        }

time of your game : S:05:43:48

https://blockchain.info/tx/2b3a6b69175251825a779bf928345a4a4525588078cdbc26abe49b35c4253505        
https://www.biteasy.com/blockchain/transactions/2b3a6b69175251825a779bf928345a4a4525588078cdbc26abe49b35c4253505        
https://www.blocktrail.com/BTC/tx/2b3a6b69175251825a779bf928345a4a4525588078cdbc26abe49b35c4253505