That is correct. Testnet ether only whilst we are in our beta, with a target launch date of March 2017 using real ether on main-net.

There are not too many rules;

1. Set the bet amount.
2. Adjust the slider to change your number (2-99) and percentage chance of winning.
3. To win, the dice result needs to be lower than your number. The dice result will be 1-100 inclusive.
4. Click 'ROLL!'

If the result of the dice roll is lower than your 'Roll under'' number (as shown in the middle colum), your win is sent to you automatically. If you lose, the contract will send you back 1 Wei. The house edge is 1% - half of Satoshi Dice.