Another few possible improvements: upgrades for clients/minute instead of the seconds between each customer, you can make the rooms and pool lanes more efficient this way ;)
It would be nice to have the upgrade screen not go away as soon as the cursor leaves the box. My mousepad isn't very accurate :p And as some others have pointed out, this is a good concept, but does need more balance when it comes to rooms/client ratios. If you want more businesses, I'd think more about what's in a vacation area. There is a swimming pool, maybe a casino, several kinds of shops, like pharmacist, clothing, shoes, groceries and so on. Keep up the good work!
I can't start the game, Java is telling me it's not safe and when I unblock it, it says "Error. Click for details." After clicking, it says "ClassNotFoundException"... :(
 "Rullo"){kind=icon}
 "Idle Power"){kind=icon}
 "Miraculous Ladybug Bubble"){kind=icon}
 "Idle Business"){kind=icon}
 "Upgrade Station"){kind=icon}
 "Heterochroma"){kind=icon}
 "Trippy Carrot"){kind=icon}
False.