Nice start. I didn't find any issues or bugs. Played the game normally, first the 3 minute shift, and then the 6 minute shift. Managed to get all the customer of both of these shifts. I've found the game quite relaxying. I liked the minigames. The clicking one, I holded the mouse with one hands, and used two fingers to click at 2x speed haha.
Got enough money to buy the two upgrades, then I level up. Tried the 3 minute shift again, and now things got a lot harder. Lost 3 customers. I would miss the new music minigame, which was the longest. Maybe when we are on this minigame, turn off, or dial down the background music, so we can concentrate better on the notes being played.
The memory minigame, doesn't this ussually first show you all the pieced, then they turn down? Not an issue regardless because there are only a few pieces. But if they get progressively harder, I think that would be at least an upgrade to buy.
Anyway, I enjoyed the game. You have a lot of room to expand with new machines, minigames, and upgrades.
Good luck!