If the internet connection failed before users pressed the Spin button, then after the game is restored, the current position (balance, round, bonus or double game) will be saved. If it happens after players clicked on the button, the system will accept the bet or make one spin.
This approach is typical for all types of entertainment with a built-in RNG (random number generator). The remote game server instantly receives information from the gaming site — it is enough just to click on the Spin image.
In card games, data is transmitted by pressing the Deal button. The rest of the system works like in slot machines and roulette.