Access to bonus levels in LEGO Star Wars is gained by gathering the so called Gold Bricks. You can collect 4 of them on each level: for completing the Story Mode, for getting all 10 minikit parts, and for getting True Jedi status in Both Story Mode and Freeplay. 8 of them can be bought in the shop, 10 are awarded for completing the bounty hunter missions, and 9 are related to episode-specific bonus levels. To sum up, you have 99 Gold Bricks to find. When you do that, you'll be almost done with the game. The only thing left will be to buy everything in the shop.
Required Gold Bricks number
Episode IV bonus.
Episode V bonus.
Episode VI bonus.
LEGO City access.
Collecting power bricks allows you to buy cheats in the Cantina. On each level there's one power brick to be found. Their locations are described in the Freeplay section of the guide. Here's the list of all the cheat codes.
Through the Jundland Wastes
Mos Eisley Spaceport
Rescue the Princess
Death Star Escape
Escape From Echo Base
Cloud City Trap
Betrayal Over Bespin
The Great Pit of Carkoon
Bounty Hunter Rockets
The Battle of Endor
Super Ewok Catapult
Into the Death Star
Cheats worth using:
Super Blasters/Super Lightsabers - it's always good to have greater firepower;
Fast Force/Fast Build - you build and use things faster;
Invincibility - great way to make your True Jedi hunt easier (when you are invincible, you can't loose any studs);
Infinite Torpedoes - a great feature for all the starship levels.
Score x2/x4/x8/x10 - they are extremely expensive, but make your life a lot easier.
Super Story. You have to complete all 6 levels of this episode within an hour and collect 100 '000 studs meanwhile. It's not difficult provided you've already beaten these levels at least twice. Just remember not to focus too much on the studs, 100k is a really small amount and you'll surely get it by default.
Character Bonus - Mos Eisley. You have 5 minutes to collect one million studs. As in any other level of this kind, invincibility is a great thing to have. It's good to use a Bounty Hunter in this one. Use his detonators to blow up the respawning shiny metal objects.
Minikit Bonus - Death Star. Another million stud in 5 minutes, only this time you're piloting a ship (one of the minikit models). Choose something fast and agile. Millenium Falcon is a cool choice, as it's bigger than some other ships and therefore it's easier to collect studs when controlling it.
Super Story. Just as in E4: 6 chapters, 60 minutes, 100'000 studs. It's a bit harder than the previous episode, but still can be done without real problem as long as you don't waste time on wondering how to solve a certain puzzle. Again, no point in paying too much attention to studs.
Character Bonus - Bespin. 5 minutes to get 1'000'000 studs. It's good to find two large groups of respawning stud sources (such as boxes or shiny metal objects) and cycle between them. Use Bounty Hunters.
Minikit Bonus - Hoth. It's good to have a snowspeeder here (you have to collect all the minikit parts on Escape from Echo Base to get it), as you can use its tow cable to blow up the best stud sources around.
Super Story. You have an hour to complete the whole episode and get 100'000 studs. It's definitely the hardest one of all the bonus challenges. Don't resign when the first two levels take too much time to complete, the second half of this episode is a lot simpler and quicker (the last two levels can be done in less than 10 minutes).
Character Bonus - Endor. You now have 7 minutes to get a million studs - no problem at all, can be done in about 3 or 4.
Minikit Bonus - Endor. It's identical to the Death Star and Hoth bonuses. You can't go wrong with the Millenium Falcon.
For completing all the minikits (18 ships, each made of 10 parts) you gain access to a hidden ship you can use in Freeplay - Boba Fett's Slave 1.
LEGO City's entrance is outside the Cantina and to open it up you have to collect 60 Gold Bricks and complete the whole Story Mode. When you are done with that, just build the large question mark shown on the screenshot below.
LEGO City is a world where Star Wars universe mixes with classic LEGO toys. Our goal in this place is to collect one million studs. Although you can see the timer on the screen, you don't have to hurry, there's no time limit. There's exactly one million studs around here, so you can't miss anything. Below I point out some of the more troublesome puzzles.
Take a ride in every vehicle you can find. Some of them are available from the spot, and some need to be built from loose bricks. When you mount a vehicle, you see a trail of blue studs - collect them all.
You can use the small bricks laying on the lawns to create flowers.
Around the place shown on the screenshot you'll find parts of a flying machine that you need to build. Use the antennas of the nearby tower to complete it (you can access it by jumping off a Dewback).
By walking around the lawn near the left end of the map you make flowers appear. Also, destroy all the trees in there.
Use the Force to complete a LEGO sign in the right side of the city.
Besides all that, destroy everything you can. Remember that it's better to use the Force on everything first. If you destroy a building before using the Force on its windows, you'll loose the chance of getting all the studs. Also, remember to throw a detonator here and there.
HINT: LEGO City is a cool bonus feature, but completing it doesn't seem to be giving you anything in particular. The money you collect in here doesn't stay on your account.
LEGO Spigot is the ultimate unlockable in the game, one that requires all 99 Gold Bricks to be collected. When you have them all, you can built the spigot outside the Cantina. To achieve 100% completion of the game, you now have to buy everything from the shop, including very expensive stud multipliers. To get the money for that, place your character under the Spigot and just wait for the cash to flow. You can also turn on the second player character and place him on the other side of the Spigot, that will speed things up.
Hundreds of millions of studs are a matter of seconds when you have x3840 multiplier.