I purchased this without realizing it was an iOS/Android game. For a portable game Echo prime isn't half bad. I can see how the gameplay would lend itself well to that platform. However, the features that make it ideal for a cell phone don't translate well to a home enviroment. The game is clearly intended to be played in 10 to 15 minute spurts and that shows in the level design and make-up. Levels are blazingly short and incredibly repetative, most likely to compensate for the presumed limited space of a phone or tablet. Also, the designers left in many of the touch related instructions. During the initial traning mission the player is encouraged to "tap a place on the ground to move there" or to "Swipe to dodge!"
Echo Prime's gameplay tries to find a home somewhere between a clickfest like Diablo and classic arcade Beat-em-ups like Streets of Rage but it misses the key notes that make those two genres enjoyable. You gain money from grinding missions which you use to buy weapons and armor which you then grind kills on to get "Echoes" which are essentially spells that can level. It's a fairly steep and obvious treadmill. Though, the only incentive I can see for continuing to upgrade your gear is the chance to unlock new Echoes. You aren't encouraged to upgrade your gear because the enemies are hard, in fact quite the opposite. I was able to play to level 8, about an hour in to the game, without purchasing new items. The AI is too predictible or, in some cases down right dumb, to pose any type of a threat to a competent player.
Lastly, the story: more spefically the almost complete absense of one. You're a guy on a ship flying around space and beating up aliens, pirates and robots whose character models don't really differ that much.
All in all, I can understand how this would be an enjoyable game on a mobile platform but at the end of the day there is enough substance or depth here for the game to have lasting appeal.