At first—assuming that you choose the game’s Career mode—it might be hard to understand why Tapulous decided to sell Metallica Revenge as a standalone application rather than as an artist-themed In-App Purchase for the recently released Tap Tap Revenge 3. Other than a tweak that lets you earn and hold up to two 16x point multipliers at once, tapping specially colored balls to grab them and the sides of the screen to activate them,…
