Sentinel 2: Earth Defense set a high water mark for what was possible in an iPhone tower defense game. It took a basic formula, added great graphics, and mixed in a few novel and substantive tweaks to set it apart from other games in the genre. The third iteration in the franchise, Sentinel 3: Homeworld, continues to build upon that base and adds even more innovations. Rather than reinventing the series, it seems to be happy trying to perfect it and is successful in doing so.
At the most basic level, Sentinel 3 is a tower defense game. You build a variety of towers designed to slaughter horde after horde of encroaching enemies. Success involves choosing the proper towers for the job and placing them where they are most effective. If you’re not interested in games that involve a lot of planning and micromanagement, this game is probably not for you.
This game’s a blast!
All of the innovations from Sentinel 2 are in place in Sentinel 3. You can build drones to help you gather resources and repair your defenses. You can also use energy that you accrue to call in powerful assistance from above, such as missile strikes and healing beams. The use and timing of these temporary effects is crucial to your success, especially at the higher difficulty levels. Someone looking over your shoulder might mistake this game for a real-time strategy game like Starcraft 2 when your defenses are firing on all cylinders.
The most noticeable addition in Sentinel 3 is the commander unit. This mechanized soldier protects your gates on the battlefield and can be upgraded with more powerful attacks and healing abilities. He can also be moved around to help out where your defenses are weakest. This, along with your orbital attacks and managing your drones, helps keep you busy and avoids the common pitfall in tower defense games of being left to sit back and watch the enemy throw themselves on your defenses while you have nothing to do.
Beam me up, Scotty..
Another feature that freshens up the game are the light RPG elements between stages. As your commander levels up, you can choose which attributes to improve. You are also now limited as to which towers and orbital effects you can bring into each level. Certain levels contain enemies resistant to specific attacks or have a layout that makes certain towers more useful than others. Choosing what to bring into battle with you is a fun and strategic addition.
Unfortunately, a few bugs crept into the game. The in-game music is great, but becomes extremely repetitive. Unfortunately, the game disables background music and the ‘iPod Music’ feature did not work for us. Also, Apple’s Game Center has been included along with OpenFeint. However, we had problems unlocking achievements on Game Center. Achievements that would unlock in OpenFeint would not consistently unlock in Game Center. Hopefully these issues can be patched in a later version.
If you’re not totally burned out on the genre, it’s time to give Sentinel 3: Homeworld a try. It looks and plays great, and throws in a ton of levels, weapons and upgrades to play with. Sentinel 3 stands head and shoulders above the droves of free and $.99 tower defense games on the App Store, and is easily worth the few extra bucks.