The Tactics of Bit City
The game is so simple, you buy buildings, tap to upgrade them, which then earns you more money. You can also buy cars, and eventually planes and boats. After 8 levels of Earth, you are brought to the Moon, where the strategy and gameplay actually differentiates itself from its mother planet.
On Earth, upgrades are overwhelmingly overpowered, and so to quickly win a level, you should always focus on buying out all the upgrades and then buy buildings. This is balanced out on the moon, where upgrades and buying buildings are equally as important.