To achieve 100% completion you must do the following:
Purchase all 96 characters.
Purchase all 20 Red Bricks.
Unlock all 70 Gold Bricks. To unlock them you need to:
- Complete all levels in Story Mode. (15 Gold Bricks)
- Complete all levels in Free Play and gather all Golden Manuals. (15 Gold Bricks)
- Collect all 15 pairs of Pants. (15 Gold Bricks)
- Achieve the Special in all 15 Story/Free Play levels. (15 Gold Bricks)
- Unlock the 10 Gold Bricks in the Bonus Room. (10 Gold Bricks)
Here are the locations of the gold bricks in the bonus room:
1) In the fish tank in the back left corner up high.
2) Head up to the top left and climb the plant and head up past the mp3 and push the truck over the edge.
3) Complete the hacking mini game straight ahead.
4) On top of the desk ahead is a corkboard, all the way at the top.
5) On top of the red chest in the back right corner.
6) Behind you is a grate that you can melt off, inside is the gold brick.
7) Behind you is a ramp made of LEGO books, inside the circular tube.
8) Underneath the bed is a box, pull it down and build all the LEGO pieces and the gold brick will be in the box.
9) Collect 1,000,000 studs in the Bonus Room and a Gold Brick will appear.
10) Get in the car that you used to knock the books over and drive it over to the build station and you will see 5 equal looking signs on the floor. Follow the stud trail and once you get back to the start the gold brick will be in front of you.