Beware, there are lots of problems with dice, especially when there is a relatively low hash rate (e.g. most altcoins). An attacker with enough hashpower to solomine could steal fairly easily. I can't find the article detailing how a miner could defraud you but it goes something like this:

1. Attacker has 250 BTC
2. Attacker makes 2 transactions from one input, but doesn't publish them
   
   1. betting 250 BTC on Satoshi Dice 50% 1.98x
   2. sending 250 BTC to another address owned by attacker
3. Attacker solo mines bitcoin at 0.1% of network (reasonable expectation to block: 1 week) with transaction b included
4. Attacker finds a block and holds it while sending 250 BTC bet to satoshi dice
5. Within seconds, attacker knows if they've won 245 BTC or if they've lost

If attacker loses bet: they publish the block, effectively unspending the transaction sent to satoshidice

If attacker wins bet: they discard the block, since 245 BTC is greater than the 25 expected from the block

Also, it's possible for people to game these 0 confirmation games by not paying a fee to the game and sending a double spend with a fee. See: https://bitcointalk.org/index.php?topic=130764.0

Any dice game you use should be deposit based, like just-dice.com