Defense Grid: The Awakening

Defense Grid: The Awakening is a tower defense video game developed by Hidden Path Entertainment for Windows and Xbox Live Arcade on the Xbox 360. The game was one of the titles promoted by Microsoft during their Game Developers Conference keynote speech on February 20, 2008. The game was released for PC on December 8, 2008 and for Xbox 360 on September 2, 2009.

The Mac OS X version of Defense Grid: The Awakening shipped from Virtual Programming on July 7, 2010.

Players must defend military bases from waves of attacking aliens by positioning a range of tower-based weaponry. New levels provided as downloadable content have been developed in the two years since the game's initial release. All reviewers praised the game, with many noting that the quality of the game was high for a budget title.

Plot
The story is based on alien invasion of a planet that has a dormant defense grid. As the player is re-activating the defense system with the assistance of a computer to control the machinery and with only limited resources, the aliens attempt to steal power cores. Power cores are "tiny floating orbs" that provide vital power to the defense grid. Once all power cores have been stolen the game is over. Only one power core need be remaining when the last wave of aliens is killed to complete a level.

Defense Grid is set in the distant future. Most levels feature ancient ruins with defensive military bases built amongst the decaying structures. The game was originally planned to be set amongst an urban environment which has been ravaged by war but that was changed to something more original. The main character in the game, which is called the Entity, is a computer with human-like qualities that wants to protect his homeworld from destruction.

Gameplay
The player must defend power cores, which are usually located at a power station, from the invading enemy using ten different tower types. Tower construction is limited to specific platforms. Towers cannot be destroyed by the enemies. The ten tower types are as follows:


 * Gun: A versatile machine gun turret which is especially effective against shielded and flying enemies.
 * Cannon: A long-range projectile weapon which has a low rate of fire but inflicts heavy damage. This weapon is effective against strong and shielded enemies and can also hit flying enemies
 * Inferno: Flamethrower-based tower which is effective against large groups.
 * Laser: Laser that inflicts damage over time and continues to burn enemies after leaving its firing radius. It is effective against fast enemies.
 * Tesla: This weapon fires lightning bolts and deals more damage the longer it is charged. It is effective as a last line of defense at exits.
 * Missile: An anti-air missile tower that cannot target walking aliens.
 * Command: A tower that increases revenue per alien killed and reveals stealth units within its radius.
 * Temporal: A tower that emits energy pulses and dramatically slows enemies within its radius.
 * Concussion: An area of effect weapon that fires explosive grenades. It is effective against large groups.
 * Meteor: A long-range tower that launches a superheated fireball at the enemy. It is effective against large groups.

Good tower placement is the key strategic object of the game. Each tower has unique trade-offs that affect ideal placement, such as line-of-sight or ballistic trajectory fire; a large area of effect or damage over time; and minimum and maximum ranges. The "insectoid" enemies arrive in waves and travel along elevated pathways which connect various structures found at the bases. Killing enemies earns resources, which can be used to build more towers and upgrade towers toward two stronger levels. Depending on the tower type an upgrade will provide a more powerful attack, an increased rate of fire and increased range. Tower strength is denoted by the colours green, yellow and red. Towers may be sold (removed) if resources are needed or a player wants to alter pathways. Resources earn interest with the rate increasing the more resources are obtained. The tower defenses are supplemented by the use of an orbital laser which completely destroys all aliens in its blast zone in one strike. The laser is not available in early missions and takes time to recharge.

During the game, the player battles fifteen types of enemies, each with unique capabilities and strategies. Some aliens are protected by shields which have to be destroyed first before the alien's health will decrease. The aliens will always take the shortest route and some of the aliens fly, requiring towers with aerial weapons for defense. The invaders able to carry between one and three power cores. If an alien is killed while carrying a core, the orb will slowly float back to the power station. While returning the power core can be grabbed by an alien which will then head for the exit without reaching the power station. A ticker at the top of the screen advises players of the approaching alien wave's formation. In the PC version of the game, pressing the F key will speed the game up for as long as the key is held, the T key will show weapons range and aerial aliens path and the Backspace key may be used to revert to a previously, automatically saved checkpoint. Defense Grid can be viewed at three different levels of zoom. When a level is successfully completed a set of challenges using the same map become available. Players earn medals depending on how well they complete a level. A Steam leaderboard that provides a comparative ranking of player's game scores and other statistics is available.

Development
During development, which started in late 2007, the game was known as Last Stand. The development team were aiming to create a standard tower defense game but in 3D, downloadable and with high production values.

The game was created by Mark Terrano, the lead designer of Age of Empires II, and uses the Gamebryo engine, as used in The Elder Scrolls IV: Oblivion, Civilization IV, and Fallout 3. Defense Grid also uses the Scaleform GFx user interface engine. The lead designer for the game was Michael Austin. Lex Story contributed heavily to the design of the 30 different towers which appear in the game.

Downloadable content
Defense Grid: Borderlands was the first set of new levels provided as downloadable content. Defense Grid: Resurgence was announced on 29 May 2010 by Hidden Path Entertainment. The downloadable content is made up of eight new maps, released in instalments of two maps each week throughout June 2010. Each map includes a campaign mode and four challenge modes. The content is available for PC and Xbox 360.

Reception
On December 16, 2009, Gamasutra included Defense Grid on its Best Of 2009: Top 5 Console Downloadable Games. The April 2009 issue of PC Gamer awarded Defense Grid a 90% and an Editor's Choice badge, stating, "Defense Grid is such a charming and challenging experience that shouldn't be missed by tower defense fans. Even if you're not a fan, it may turn you into one." GamePro said, "Defense Grid: The Awakening is a prime example of that sudden transformation of taking an unoriginal, well-known style of video game and turning it into a masterpiece for your PC", awarding the title 4.5 stars out of 5. IGN ' s 8 out of 10 review stated, "It's an addictive time suck that will have you wishing for more once you've wiped up the last alien." The GameShark review thought Defense Grid was a "solid, well-rounded strategy game". A Thunderbolt Games review thought the game was "a charming little tower defence title with a decent story and challenging gameplay." A Gamervision review thought the later levels could be "frustrating difficult" but liked the replayability from challenge modes.

The Destructoid review lamented there being only 20 levels. A number of reviewers felt the game would be much better if it came with a level creator. At least one review drew attention to the lack of a rotatable camera. The Gamepro review felt some gamers might find the game a little repetitive. A few reviews noted the lack of any multiplayer options. Another review noted that navigating the menus can be a little clumsy.