Path Drawing & Tower Defense Meet in A.I.R. Defense

AIR DefenseThere are plenty of tower defense and path-drawing games on the iOS touchscreen, but Chillingo and developer Colorbox have brought the concepts together in a unique retro arcade-style iPhone game, A.I.R. Defense.

The game, released on the 14th, succeeds in pushing the hybrid genre forward, with the main drawback being somewhat rough controls.

Long story made short, aliens are invading and the player has to stop them. Granted a single base with only a handful of air fields, players must construct various aircraft in order to destroy an ever-growing waves of enemies. This is where the tower defense mechanics come into play. Each aircraft is sort of like a tower in that they come with various attributes and special abilities such as speed, ammunition capacity (more on that in a second), damage, and so on. As one might expect, the stronger the unit, the more it costs, and income is earned by destroying enemies or picking up “supply” drop offs that friendly, non-player planes periodically drop.

PathsLike in a tower defense game, the enemies will stream onto the board (though not following a preset path), and should they reach the player’s base, damage will be incurred. Failure occurs once the health of the base has been depleted. This is where path drawing comes into play.

Unlike a tower defense game, the aircraft (“towers”) do not automatically attack. Players must draw a path from the airfield it is waiting at to an enemy. The challenge of this comes in at multiple levels. For starters, players obviously want to attack the closest target. However, some enemies might take multiple hits, while others fire projectiles that can actually hinder or destroy friendly aircraft. This means that players must not only try to steer their units with a path that avoids enemy fire, but must properly choose targets based on enemy type, friendly unit used, and proximity.

To add further challenge, each friendly air unit holds a finite amount of ammunition that is only increased upon upgrading. For example, the initial helicopter unit can only fire one shot before having to fly back and reload (which takes a few seconds). Once this unit is upgraded, it can be used to fire multiple shots, which means a path can be drawn from the base, to one enemy unit, to another enemy unit; destroying both. The downside to this, is that players lose some control and should alien projectiles hit a friendly unit, an upgrade level will be lost. If it is level one, it will be destroyed.

ChainsAlready, it is clear how chaotic battles can become, so in order to mitigate this somewhat, the user’s base comes with a handful of special abilities that can be activated periodically and used as a sort of desperation defense. As an example, a lighting-style power-up can be utilized that will vaporize any enemies that come too near the player’s base for a limited time. In addition to this, enemy units are highly volatile. Should one explode near others, they will also be destroyed, allowing for chain destruction that will dramatically boost one’s score.

Since A.I.R. Defense is a Chillingo game, it is connected to the social gaming network of Crystal. As such, score becomes an element to add longevity to the game as users can connect with friends and compete together, or globally, via leaderboards. Moreover, the Crystal network allows for a number of achievements to be unlocked as well.

As for any other elements of A.I.R. Defense warranting mention, the game also incorporates a survival mode where users attempt to, well, survive as long as possible, and there are even a few boss alien units that add some extra surprises for the player.

Central BaseThere is, however, one very unfortunate downside. The controls for this title are highly temperamental. All too often would we attempt to tap on a friendly unit and draw an attack path only to have the game not respond or the unit quickly take off and instantly land (as if a tiny path was drawn on top of it). To make matters worse, A.I.R. Defense is a very fast-paced game. When it takes two or three tries to get the game to do what one wants it to do, the alien units are already knocking on the front door. In early levels, this isn’t enough of a problem to cause complete failure of a level, but it is no less aggravating as it makes things unnecessarily more difficult and can drastically hinder high scores.

Overall, A.I.R. Defense is a fantastically designed game that uses the best elements of both tower defense and path drawing applications to create a very unique feeling experience — worth the $0.99 for many gamers. Without even going into detail of the various types of friendly and alien units, it is clear how deep the game can get in terms of both strategic and tactical decisions. Nevertheless, no matter how good a design is, poor controls can ruin everything, and with this first iteration of A.I.R. Defense, the touch controls feel highly unresponsive, leading to a disappointing first impression. Thankfully, such is an issue that should be more easily remedied than a core design one.