Sentinel Ups the Ante for Tower Defense Games

Sentinel: Mars Defense (AppStore Link)
User Reviews
Sentinel: Mars Defense
Developer: Origin8 Technologies Limited
Price: $0.99 Download on the App Store

sentinel iphone tower defense appSentinel - Tower defense (TD) games have proven to be a genre that can be done extremely well on the iPhone. The cream of the crop in this genre currently includes titles such as Fieldrunners, 7 Cities, The Creeps, and they all have their own quirks that make them unique. That hasn’t deterred Origin8 from delivering its spin on the space with the release of their new title. Their science fiction themed Sentinel is the new kid on the block, and it’s looking to prove itself worthy of your $5.

There are two primary modes in Sentinel named Assault and Endurance (has to be unlocked) to get through. Assault (think campaign mode) provides up to four difficulty settings that be chosen over the course of the game’s two maps.

Your job in Sentinel is to place weapons and defenses on a map to destroy waves of alien monsters that have different strengths and weaknesses. Upon seeing the enemy types, it’s your job to layout a variety of weapons and defenses to counter what the enemy is bringing. For example, flying alien critters are best handled by “Laser” or “Beam” tower defenses while land monsters are best handled by “Bomb” and “Slow” tower defenses. Killing enemies gives you cash to upgrade towers or buy new ones altogether. With each passing wave, you can earn points that accumulate over time. When your game is over, you can upload your score to online leaderboards to see how you compare with folks all over the country.

Sentinel adds a few sprinkles to the TD formula that is worth nothing. Most TD games lay out a map without obstructions allowing enemies to freely navigate through the path to attack your base. Sentinel adds in obstructions and barriers that enemies have to destroy throughout the map before they can continue unimpeded to your base. This adds an additional layer of strategy as you’ll have to make choices about concentrating your towers around those barriers or spread towers all over the map. Cool repair droids (which cost money) can be bought to repair barriers that the enemies are chipping away at as well. Last point in this vein, Origin8 has integrated functionality to speed up Sentinel by pressing an onscreen toggle button. Good stuff all around here.

Getting around in Sentinel is very easy, especially for those of you that are familiar with TD games. Adding a tower to the map only requires the tap of a tower in the bottom of the horizontally oriented screen and a drag motion to place it onto the map. Upgrading or selling off a tower is as simple as tapping it, and it’s extremely responsive. Unlike many other tower defense games out there, you can use iPhone’s native pinch and expand finger gestures to zoom in and out on the map. Overall, I found getting around Sentinel very intuitive and I can’t pinpoint a single issue I have with the controls.

Sentinel looks awfully pretty. Everything about the game oozes polish and detail which is always refreshing. The 2D sprites animate well and it produces a great look when they are placed on top of the gorgeous pre-rendered maps. Each of the three maps have a distinct look that does a reasonable job of keeping things fresh. My only issue with the graphics is that more dramatic transformations should occur when upgrading towers. I’ve had some problems identifying my towers in their various stages, so I'm hoping an update can address this small issue.

As you can tell, I adore Sentinel. It exhibits so many qualities that define what a AAA production is. The question is whether a three map TD game is worth $5 when all its main competition falls between $1-$3. I think it does (ever so slightly, though a 4th map would remove all doubt on value), but I can see some buyers feeling a little jipped on content. Sentinel has a free trial available for everyone to try out, but I whole heartedly recommend Sentinel to fans of the tower defense genre.

Image Gallery: Sentinel: Mars Defense

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