To unlock this you need to have:
• Complete all missions in story mode
• Collect all the mini-kits for each mission/level
• Complete all Space Combat Missions
• Complete all Bounty Hunter Missions
• Complete all Republic Assault Missions
• Complete all Separatist Assault Missions
• Unlock/Purchase all characters
• Unlock/Purchase all vehicles (this includes, ships, ride able weapons etc...)
• Obtained all Gold Bricks
• Obtained all Red Bricks
At each computer console, you will see the games percentage and time played, so you can easily keep track of your completion percentage