Choices made by main player characters throughout the game can affect their alignment to the light or dark side of the Force.
Alignment has a hidden point value between 0 and 100, representing the extremes of dark side mastery and light side mastery respectively. Main player characters begin the game at 50, with dark side actions subtracting from that value and light side actions adding to it. All dark side and light side actions have a point value assigned to them:
|Action||High dark||Mid dark||Low dark||Low light||Mid light||High light|
However, these point values are adjusted based on the current alignment of the main player character:
|Very dark (0-14)||Dark (15-39)||Neutral (40-60)||Light (61-84)||Very light (85-100)|
Feedback only gives a vague indication of how many points have been added or subtracted after an alignment shift:
|+10||You have moved a great deal closer to the light side of the Force.|
|+(6-8)||You have moved much closer to the light side of the Force.|
|+(1-4)||You have moved closer to the light side of the Force.|
|-(1-4)||You have moved closer to the dark side of the Force.|
|-(6-8)||You have moved much closer to the dark side of the Force.|
|-10||You have moved a great deal closer to the dark side of the Force.|
When viewing character models on the character screen an arrow indicates their position on the meter to their left, while an icon will appear on the status bar to their right when light side or dark side mastery is achieved. The background and their facial expressions and stances also indicate where they are on the spectrum of good and evil:
Main player character portraits also change as alignment shifts towards the dark side of the Force: from top to bottom, appearance corresponds to alignment 41-100, 31-40, 21-30, 11-20 and 0-10.
Some items cannot be equipped unless a character has progressed beyond a certain threshold to either side: items restricted to the dark side cannot be equipped unless a character’s alignment is 0-40, while those restricted to the light side cannot be equipped unless it's 60-100:
|Item||Restricted to: Light Side||Restricted to: Dark Side|
|Head||Circlet of Saresh||Tulak Hord's Mask|
|Hands||Marka Ragnos' Gauntlets|
|Robes||Qel-Droma Robes||Darth Revan's Robes|
|Star Forge Robes|
|Power crystal||Crystal, Solari|
Some Force powers are inherently light or dark in nature, and cost more Force points to use if a character is of opposing alignment:
The alignment value thresholds in the manual are not entirely accurate (those above are derived from the game itself). Light side power costs increase the further to the dark side a character is (and vice versa):
Use of Force powers of opposing alignment doesn't normally affect a character's alignment.
Mastery bonuses vary according to Jedi class and alignment:
|Jedi Guardian||Jedi Sentinel||Jedi Consular|
|Light side||Strength: +3||Constitution: +3||Charisma: +3|
|Dark side||Damage: Physical, 1-8||Immunity: Poison||+50 Force points|
These bonuses are only granted to the main player character unless on Xbox. They're not permanent, but only granted when alignment is at either extreme of 0 (dark side) or 100 (light side): a dark side action results in a light side mastery bonus being lost (and vice versa), although it can be regained with appropriate action.
Alignment of party members doesn't change as a result of their own actions or those of the main player character.
However, comments on the choices of the main player character differ depending on the alignment of the party member, and some light side party members may actually intervene to prevent some dark side actions.