This app was mentioned in 1 comment, with an average of 2.00 upvotes
https://play.google.com/store/apps/details?id=com.cg.vendingmachinetimelessfun
The idea behind the game is to tap on coins until you have enough to purchase the item the mission is calling for. Once you buy the object, by tapping on it in the machine, it drops to the bottom where you collect it and complete the mission. You proceed at that point to the next mission after viewing an ad.