Games that revolve their play and mechanics around music are something special. What's even more special are those games that allow you to use your own music library as not only this ensures you have levels based around music you enjoy listening to, but it creates almost limitless content. Beat Hazard has been around on Steam for a while, turning any song in your library into an adrenaline pumping twin stick shooter. Now for a lot of people the visual assault of this game made it unplayable, and while the iphone version maintains this unique visual bombardment, the smaller screen lessens any disorientation or nausea one might experience sitting up close to a monitor or television. Still, the seizure warning displayed as the game loads up is there for a reason.

If this review hasn't scared you off already, you'll be happy to know the game experience itself is amazing, especially the changes made for the iPhone platform. There is a beginner and pro mode and really all this means is that beginner mode removes the right control stick, and shoots at incoming enemies automatically. This creates a much less stressful play as you only have to worry about dodging all the incoming madness to the peaks and valleys of your favorite song.

The goal of the main game is to survive the length of the song. You start the game by choosing the type of game, your track, and the difficulty (with harder difficulties needing to be unlocked). From there the music and level starts. Destroying enemies will increase your score and multiplier (as will completing objective bars such as chaining together kills or spending enough time without shooting). Enemies will drop all manner of power-ups such as score and multiplier boosts, power upgrades to your gun, and most important of all, volume boosts. See the music will always start quite faded, and it's only through surviving and collecting all these boosts that you get to enjoy the music front and center.

It's a nice gradual shift alongside the intensity of the level too. As the music gets louder, more and more dangerous enemies will litter the screen (along with boss fights), and your weapons get crazier, along with all the lighting and particle effects upping the ante. By the last minute of the song your whole mind is being assaulted by the visuals, the music, and your determination to survive. So much so that when the level ends, and your rank is being upgraded due to your score, it takes a minute or two to return to reality, and select a new perk to unlock before you pick another song to start the whole thing over again.

With multiple modes to try out, perks to unlock, ranks to acquire, and an entire music library unique to the player to work your way through, Beat Hazard Ultra is a must own for action gamers, and fans of games that use their own music. The controls are superb, and if you can handle what the game throws at you, there's no reason not to give it a shot.