Wish I was never shown his game
This game is as simple as they come but horribly addicting. While getting gems are hard to come by for new powers and heroes, the pacing of coin farming easily allows you to level what you have in order to press on area after area. What really helps the game is being able to let it sit and have you characters farm coins. I leave the game open for a few hours and easily end up with 100k+ coins which is really helpful.
Tyadres about
Tap Heroes - Idle Clicker