Call of Duty: Heroes takes a page from such successful tower defense titles as Clash of Clans and Boom Beach. Instead of parroting both titles, this free to play release takes that inspiration and forges its own path. If you're ready to devote weeks and maybe even months to an app, Call of Duty: Heroes holds an ample amount of firepower.

The adventure kicks off with a brief tutorial on how to attack different fortresses and build your base camp. As with most farming and tower defense-based titles, Call of Duty: Heroes runs on a touch and tap control mechanic. Thus, navigating your way around the game is easy as pie, and the only real variance occurs when you are controlling the heroes that you employ during the mission. Once you tap your troops and place them on a specific part of a battlefield, they are programmed to attack and destroy the nearest building or weapon. Although heroes serve the same function, you can slide your finger to a certain section you want obliterated.

Heroes are invaluable to your missions, especially if your selected troops are killed off during a PVP or a single player mission. Even if you lose your entire squad, you can still navigate your selected heroes to elude a base's weaponry and destroy as many buildings as possible. My personal strategy is to have my troops storm the proverbial castle and then bring such COD vets as Soap and Wallcroft to finish the job.

Activision

The adventure's most alluring asset rests in its ample variety of gameplay. If you are a straight tower defense enthusiast, survival mode pits your base against waves of enemies. Strategically placing your weapons near buildings and what you believe are high-volume kill points ensures a longer stretch of survival. Since you're not attacking other people's bases, survival mode is actually a passive, observational experience. If you get bored from each succeeding wave, you can always speed up the action by tapping on the blue icon on the lower right side of your screen. Since Call of Duty Heroes also gives you a 360 degree view of your battlefield, as well as zoom functions, I spend most of my survival mode time tinkering with the in-game camera (a task done with the simple pinch of your fingers).

Activision

For action junkies, the PVP and campaign modes serve as the meat of your combat experience. Once you join an allied organization, your team members can aid you in either missions. Both battles, however, nurture different aspects of your skill sets, as PVP missions help you accrue reputation and experience points for leveling up. Reputation points are only available in PVP mode, but if you're simply looking to earn huge amounts gold and oil, campaign mode is the best way to proceed. Although both versions apply the same gameplay dynamic, getting the chance to figure out which kind of warrior you are (do you battle for guts and glory or for the currency?) is one of Call Of Duty: Heroes' many pleasures.

Activision

If battle fatigue ever sets in, you can spend most of your time diving into the title's diverse farming elements. There are multitudes of mines, turrets, as well as training and research compounds to build on your base. Barriers can also be purchased and upgraded to protect your command center, and your troops, as well as your heroes, must also be upgraded as your campaigns get reach a higher danger level.

With so much to do in Call of Duty: Heroes, it's easy to get lost within this experience for hours, and thankfully this freemium experience isn't a rip-off. A green material named celerium is used to speed up your building process, and since most of the areas on your base will be under construction, a ton of celerium is really what's needed. If you don't want to spend any money on the game, all you'll need to do is purchase your building or weapon and just wait out the hours until their completion. Most of your currency will be accrued by your missions and your base's continued development, so paying for premium items is a luxury and not a necessity.

Activision

Though it can be enjoyed as a pick up and play title, Call of Duty: Heroes is a tower defense journey that also welcomes full immersion into its universe. Whether it's building your base and training the troops, protecting your home ground, or waging war on your own, Call of Duty: Heroes simply never lets up. Call of Duty is an ever growing franchise that now places iOS enthusiasts in its sights and thankfully doesn't miss the mark.

This review is based on a downloaded copy of Call of Duty: Heroes for iOS. In-game rewards were also provided by the publisher for this review.

App Store Link: Call of Duty: Heroes for iPhone and iPad | By Activision I Price: Free | Version: 1.1.1 | 92.7 MB| Rating 12+

8.5 out of 10 arcade sushi rating