My favorite time waster on my phone lately is Coin Dozer. It's like one of those arcade coin pushing machines. You play with the coins you push off and if you run out it generates a new coin every 30 seconds or so. If you want a bunch of coins you can fill out a survey, download an app, or buy them directly. But at a certain point once you've leveled up some perks/bonuses you eventually start gaining coins instead of losing them. I have something like 7000 coins right now. The scheme seems to be broken as it's typically people heavily invested in a game that purchase things, but in this game the more you play the less of a need there is to purchase.