This submission is for Caesar's Palace for the Game Boy, a gambling simulator that is very no-nonsense and straightforward unlike other casino games of the time (Vegas Dream, Vegas Stakes, etc.) You get different endings (basically vehicles) based on how much money you leave with, so we get the best ending which is the red Ferrari-looking sportscar.
The red sportscar requires $140,000 and we start with $1,000. The game has a multitude of different casino games: slots, video poker, blackjack, roulette, and the big spinny wheel. The RNG in this game is... different from the NES version. NES stops rolling the RNG when you pick a game. GB version keeps on rollin' so it gives us frame targets to shoot for.
Looking at the games, the only real possibilities are:
Roulette: Hit something to get some cash, then hit a 36:1 spin to get to $140k. This is slow as the wheel spin animation takes a while.
Video Poker: 5 coin Royal Flush in one attempt. I don't think this is even possible in the game, let alone fast enough.
Slots: $500 slot jackpot would pay $100k, so you'd need that and something else big, and I believe this would take too long.
Blackjack: WAY too slow since we have no big odds.
That leaves our savior, the big wheel. We open with $100 on Cleo and spin on a specific frame to give us $4000, then put enough on Caesar to be able to hit the big bet with a frame perfect spin. One frame later is 2:1, and we can't hit it earlier.
This should be the optimal path. I ran through a bunch of seeds on Slots and Poker, but wasn't able to find anything lucrative.