Does anyone know what's the time interval between gem balloons? or are they totally random?
Totally random. Based on my own experience: no gem balloons for more than a month, then 2 or 3 in a day.
http://trainstation.wikia.com/wiki/Category:Station_Management#Balloons
http://trainstation.wikia.com/wiki/Balloons_Test
Ste_Di Thanks for that page, i just updated Category:Station_Management#Balloons to link to it 😉 👍