Mass Effect - Uncharted
This game uses the Uncharted Worlds rules except as modified by these web pages.
Advantage / Disadvantage: (New System)
When the GM determines that the circumstances of a die roll are more difficult than is usual, the player rolls with "Disadvantage." When the GM determines that circumstances give the player a greater than usual benefit, the player rolls with "Advantage." To roll with Advantage, roll 3d6 and choose the 2 best. To roll with Disadvantage, roll 3d6 and choose the 2 worst.