With its previous releases, Hook Champ and Super QuickHook, RocketCat has carved out a unique niche for itself on the iPhone. Now, with Hook Worlds, the developer has produced yet another exciting grappling hook platformer, while pushing the genre forward with some unique innovations.

For those not familiar with RocketCat's "Hook" line, Hook Worlds is similar to running games like Canabalt or Robot Unicorn Attack. Your character is constantly moving, but it's your job to help them clear assorted obstacles. What makes the "Hook" games different, however, is that instead of a jump button, players have a grappling hook that can be used to swing from pretty much any surface.

The previous entry in this series, Super QuickHook, was more a traditional platformer, boasting individual levels with defined endings. Hook Worlds eschews that kind of structure, preferring instead to build upon that game's Avalanche mode. Like Canabalt levels are randomly generated and infinitely long, making the game's object more about speed and fluidity of motion than reaching a specific goal.

Hook Worlds might closely mimic a game mode in Super QuickHook, but it brings with it enough new features to more than justify the extremely reasonable price of $0.99. In the earlier game, users had their trusty grappling hook and a pair of rocket boots to utilize when the going got tough. Hook Worlds ups the ante by giving each of its three playable characters unique power-ups to get through their stylized levels.

The first character, Theodore "Gramps" Hooker, possesses the aforementioned rocket books. This gameplay option is the most traditional of the three, with users trying to last as long as they can before the evil floating eye on their tail catches up with them. Gamers in this mode go for speed, racking up points for every second they stay ahead of their pursuer. While there isn't anything new about this option, the gameplay is as crisp and exciting as ever.

Hook Worlds mixes things up a bit with the second gameplay option, as users step into the boots of Zelle the Bounty Hunter. Instead of rocket boots, Zelle has a trusty revolver that she can use to shoot through barriers and take out ghost pirates, which leave behind coins and treasure. While there's nothing chasing you in this version, Zelle has a limited amount of life, which gets chipped away every time she runs into a ghost or lands on spikes. Points are generated based on how many coins gamers loot before they run out of life.

The first two play modes in Hook Worlds are fun and extremely replayable, but the most exciting part of the game is taking control of Cybergnome 202X. As a flying ship chases behind him, the gnome must navigate a futuristic city with the help of his grappling hook and a gravity reversal belt. It takes some time to get used to the best way to work it, but gravity reversal is a great twist on Hook Worlds' classic gameplay, and can be extremely satisfying when used as part of a lengthy run.

While Cybergnome 202X is the most innovative of Hook Worlds' gameplay options, all three modes are exciting, fully fleshed-out gaming experiences that can go on as long as you manage to keep swinging, a remarkable bargain at only $0.99.

With graphics that are more NES than PlayStation 3, no one will mistake Hook Worlds for Infinity Blade. But with its classic side scrolling gameplay, the game's crisp sprite-based graphics aren't just a welcome bit of 8-bit nostalgia, they also work perfectly with the title's simple but engaging gameplay.

Like Super QuickHook before it, Hook Worlds gives gamers the opportunity to customize their characters with various hats and hooks. But, unfortunately, just like in that earlier game, these options are strictly aesthetic and do nothing to change the gameplay. This isn't a huge deal except for the fact that the equipment's presence acts as a sort of tease for legitimate, gameplay-altering upgrades.

The uselessness of its unlockable equipment is only a minor quibble, however, and does nothing to affect how fun and addictive Hook Worlds can be. With the addition of new gameplay elements and endless levels, RocketCat has improved upon an already winning formula by dramatically upping the genre's replay value.

Final Score: B+