Credit Game Suggestions.

These are a few games that I can see being fun to write and fun to play for credits, and also beautiful in the design department, they'd work perfectly with a flat design and can be beautiful if done right!

Roulette
Roulette is a casino game named after the French word meaning little wheel. In the game, players may choose to place bets on either a single number or a range of numbers, the colors red or black, or whether the number is odd or even, or if the numbers are high (1936) or low (118).

Craps
Craps is a dice game in which the players make wagers on the outcome of the roll, or a series of rolls, of a pair of dice. ... Because it requires little equipment, "street craps" can be played in informal settings. (Possibly just a dice rolling game would be fun too)

Black jack
https://en.wikipedia.org/wiki/Blackjack

Racing (Horse, duck, dog)
Horse racing, sport of running horses at speed, mainly Thoroughbreds with a rider astride or Standardbreds with the horse pulling a conveyance with a driver. These two kinds of racing are called racing on the flat and harness racing, respectively

Another way that aoki will steal our credits huh x)