Game Tables provide a custom Era gambling experience that's arguably more exciting than the retail version of the same thing. If you want special graphics to go with super exciting 500 gil bets, then stick to retail, kid.
The rest of us can trade "R" Eggs to Game Tables in Lower Jeuno for a chance to win a serious gil payout. If you don't have an "R" Egg on you, you can buy one from them for 99,999 gil.
Once you commit the "R" Egg via a trade to Game Table, you get a randomized roll and your results instantly. If you roll 55 or higher, you'll end up with some gil. Otherwise, you lose! You only win the jackpot by rolling the exact, correct number. Other winning rolls, the prize is 200k.
There are multiple Game Tables in Lower Jeuno. They all offer the same "R" Egg for sale and current payout.