Dark Gaia Force

Dark Gaia Force (ダークガイアフォース) is a type of energy that appears in Sonic Unleashed. It is basically the essence of Dark Gaia in a state of pure energy. In gameplay, Sonic the Werehog can absorb the Dark Gaia Force for various effects and game mechanics. It can only be found in the game's nighttime stages.

PS3/Xbox 360
In the PS3/Xbox 360 version of Sonic Unleashed, the Dark Gaia Force appears as small energy orbs in the shade of purple and white. Dark Gaia Force can be obtained by either defeating enemies or destroying objects in the Action Stages, with the Dark Gaia Force automatically being absorbed by Sonic once it is released.

The amount of Dark Gaia Force is determined by the energy orbs' size, meaning that the larger the Dark Gaia Force orbs are, the more Dark Gaia Force will the player obtain. Equally, the tougher the enemy is, the more Dark Gaia Force will there be released upon its defeat.

In the PS3/Xbox 360 of the game, the Dark Force is used to fill up the player's Unleashed Gauge. Once the Unleashed Gauge reaches a certain point, the player is able to enter Unleashed Mode.

PS2/Wii
In the PS2/Wii version of Sonic Unleashed, the Dark Gaia Force comes in three different types called Orbs, which can be colored either green, blue or red. The types of Dark Gaia Force can be obtained by defeating enemies, destroying objects or opening Item Boxes in the Stages, though some types of enemies only release specific types of Dark Gaia Force, and objects and Item Boxes only release red and blue Dark Gaia Force exclusively. When released, the Dark Gaia Force is automatically absorbed by Sonic, regardless of type.

Each type of Dark Gaia Force has specific effects when absorbed by the player. Blue Orbs fill up the player's Unleashed Gauge and allows Unleashed Mode, green Orbs restores the player's Vitality Gauge, and red Orbs increases Sonic's Experience Points, which can used at the result screen of the stage to increase the player's Vitality, Combat, Attack Power Rack and/or acquire a new attack skill.

Trivia

 * In the PS3/Xbox 360 version of Sonic Unleashed, Chip was the one who came up with the name for the Dark Gaia Force.