Dark Gaia Force (ダークガイアフォース Dākugaiafōsu?) is a type of energy that appears in Sonic Unleashed. It is basically the essence of Dark Gaia in a state of energy. In gameplay, Sonic the Werehog can absorb the Dark Gaia Force for various effects and game mechanics.
In the Xbox 360/PlayStation 3 version of Sonic Unleashed, the Dark Gaia Force appears as small energy orbs with a purple and white shade. In the Wii/PlayStation 2 version of the game however, it comes in three types called "Orbs," which are colored either green, blue or red.
Dark Gaia Force can only be found in the game's nighttime stages. In the Xbox 360/PlayStation 3 version of Sonic Unleashed, Dark Gaia Force is obtained by either defeating enemies or destroying objects in the Action Stages: When it is released, Sonic automatically absorbs it. The amount of Dark Gaia Force is proportional to the energy orbs' size; the larger the Dark Gaia Force orbs are, the more Dark Gaia Force the player gets. Equally, the tougher the enemy is, the more Dark Gaia Force it releases. In this version of Sonic Unleashed, the Dark Gaia Force is specifically used to fill up the Unleashed Gauge.
In the Wii/PlayStation 2 version of Sonic Unleashed, the game's three types of Dark Gaia Force can be obtained by defeating enemies, destroying objects or opening Item Boxes in the Stages, though some enemies only release specific types of Dark Gaia Force, while objects and Item Boxes only release red and blue Dark Gaia Force. When released, the Dark Gaia Force is automatically absorbed by Sonic. Each type of Dark Gaia Force has a specific purpose: Blue Orbs fill up the Unleashed Gauge, green Orbs restores the Life Gauge, and red Orbs increases Sonic's Experience Points, which can used at the Orb Result screen to level up Sonic, and also factor into his Rank at the end of each stage.
- In the Xbox 360/PlayStation 3 version of Sonic Unleashed, Chip was the one who came up with the name for the Dark Gaia Force.