Addictive iPhone games tend to usually fall into the realm of tower defense games (i.e. Plants vs. Zombies), puzzle games (i.e. Cut the Rope and Angry Birds) or match-3 gem games (ie Bejeweled). So it's always refreshing to find a developer who decides to shake things up by delivering a game that adds more action to the iPhone gaming arena. Silverfish, the latest release from Chaotic Box, is proof that a casual iPhone game can also be an action adrenaline game.

Silverfish plays like a combination of old-school arcade shooter games like Millipede with a touch of Pac-Man ghost-chomping action, while at times it has the box like movement structure of the late 70s Snake and Worm games. The game pits the gamer as a Silverfish against a variety of enemies: Grubs, Claws, Flockers, Jellies and Hornets. While these names may hint at an undersea or insect game, it's more like a futuristic space-alien shooter. Your character and the legions of enemies who appear all have a neon glow and somewhat robotic design. The vibrant visuals add to the franticness of gameplay.

There are four modes of gameplay: Scavenger, Haste, Reaper and Onslaught. Each mode adds just enough nuance to make it feel like a different game, with Reaper and Haste being the two best modes. The basic principal of each mode is simple - dodge enemies, don't get killed and occasionally blow them up to clear the screen.

In Reaper mode, you start off with your POW meter (health) at 50%. Orange Power Pods will appear intermittently, which replenish your POW meter and destroy any enemies in your immediate area. What makes this game a quick adrenaline rush is that your POW meter is gradually fading away and you only have one life. So gamers are always in a mad rush to collect the next Power Pod. Every time you destroy an enemy, two Green Protons will appear, which increase the score multiplier. This is even cooler. Usually multipliers stay in the 2x or 3x vicinity. In Silverfish, the multiplier keeps increasing as long as you can stay alive. And, it's really hard to do. In Reaper mode, you also get three Time Shocks, which you use by tapping the screen with two fingers. Time Shocks push enemies back slightly and puts the time in slow motion. At first, you'll wonder what's the point of this feature, but you'll soon realize it gives you just enough time to gather your bearings and decide where to direct your Silverfish next.

If you collect enough Power Pods to power up your POW meter without getting hurt, you will become invincible. This is when the game feels like Pac-Man. Now that you're invincible, the enemies scatter and you can chase them down and destroy them.

Haste mode is even more frantic. Your POW meter drains rapidly and you only have one life. However, when you grab a Power Pod it will immediately power up your POW meter and make you invincible. It's like quickly swapping back between chasing ghosts and being chased in Pac-Man, without the confines of a maze to restrict you. In this mode, you get three Vigor power-ups that give you a quick energy boost.

Onslaught presents a slower more tactful game. Gamers start off with three lives and three bombs. The Power Pods still destroy enemies, but you no longer have a power meter. If you get hit once you die. The bombs can be accessed by double tapping the screen, similar to Vigor or Time Shocks.

Scavenger mode puts you back in the position where your life is draining over time. The difference here is that the Power Pods are only used to destroy nearby enemies, while the Green Protons double as point multipliers and health boosts.

The only downfall of this game is that the controls take some getting used to. Chaotic Box employed a moveable D-Pad control scheme. Wherever you place your thumb down and hold it, a control stick will appear. It looks like the four-button layout of the Simon electronic game. A line moves in tandem with your thumb on the 360-degree thumbstick. However, you can only move up, down, left or right. It's a deceiving structure that both gets in the way of seeing the screen and delays you from making quick movements. The game registering every new location for the thumbstick is just enough time to be devoured by one of the space-alien enemies. Add on to it the need to double tap your iPhone screen with your other hand, and you'll start to see a few problems arise. It would be nice if there were a quick button to tap to launch your additional weapons instead.

Silverfish is one game that can easily become a new addiction on the app store. Despite mildly clunky controls, gamers will quickly get used to the control scheme as their heart races trying to avoid neon jellies and devour grubs and hornets. It's addictive and one of the better buys on the app store for only $0.99.

Final Rating: B+