This is a big city. You can go straight to get to the vendor, but if you went to desert-land first there is nothing new right now. Head right and knock over a trashcan. Very cute - sweeper bots come out to clean up the trash. Take them out. In the next area, hit the trashcan - now a laserbot comes out. Continue along this path, taking out various enemies. Go up the stairs, taking care of the sweepers on the stairs. Go up into the arch.
Knock over the can from the archway. The doors will open and sweepers come out. Once all die, other doors open and laserbots come out. When you're done, head through the arch on the left. A helicopter comes up. Fire a missile at it. Head around to the left, jump across. Now go around to the left - missile zappers. There are ladders straight ahead and right. The one straight gets you a platinum bolt.
Go right, hit a trash can and climb back up. Throw a bomb down. When it's clear, go in the arch and right onto an elevator. There's a helicopter up here - missile it. Go forward onto another elevator. Head up to a 2-trash-can room. Knock one over, kill the enemies, then do the second one. There's a continue point outside.
"Hmmmm" as helicopter comes up again. He kills you VERY quickly if you're not careful. The bomb glove works really well, then throw choppers. If you've been good, you can get the chopper upgraded to multi-star around now!
When you kill him, a translocator appears. It lets you zap to a platform with a continue point. You're in a living room with your old swingshot and grind boots!
Go out the other end - a swingshot target is detected. Use the Circle button to shoot, and L1 to aim. Use it to get over to the platform. Continue on to a 2nd, then at the 3rd blue one use it to pull down a ladder. There's another translocator here, activate it. Now you're back by your ship.
Now go left from the vendor. Go in the door and use your electrolyzer. Note in this one the gates aren't all pointing in the same direction so it's a bit more challenging.
There are sweepers, kill them all. There are lasers in the next room. The next room - there's another electrolyzer spot. Then activate the crane. Use it to drop the blue box on all the sweepy things (crunch crunch) and then put it on the far left by the platform. Hopefully it wasn't marked fragile!
Go down the ladder and over up onto box. There are lasers in next room, go through. Jump across the platforms. There's a stomper on the left, kill it. Go down to the door. Head left - jump over the gap to stairs. There's yet another electrolyzer.
Carry the robot into other room with the crane and slice the second robot with him - then the other spinners - you get a skill point!! Then drop him. Get the box and put it by the big green door in the first room (i.e. the one you need to go through) to make it explode. then go back out and get the blue box and put it by the ledge to make a stair.
Now walk out and over to the box. There are stompers in the next room - kill them and the sweepers. There's an elevator on the right. Head down a curved hall.
"Clank? Don't move! I'm coming down!" The ninja pushes you down. Use the electrolyzer to free Clank. "The final digit of pi is ..." He points at the air duct, and it's a continue point. You're clank now!
Go out the door. Jump and hold X in mid-air to glide. He only has 1 health diamond. There are the microbots!! Use Triangle and select a command. Tell them to attack. Follow them.
Now you get a Bridge bot!! It can build bridges, go figure. Go cross the bridge bot and tell the others to follow. Now tell them to attack. Next you find a lifter bot. Go back to the orange thing and ask him to lift it. Go through the gap. Time to attack! Make a bridge across and then attack again.
You find a house with the #2. Say enter, and the door opens. Walk around to the blue spot and get Ratchet. You're told that all missions are completed.
Note that now that you're "together again", you can do r1 and X for uber jump. Jump onto the ledge and then up again to go up. Now run R1 and X to get across gap. left and ahead. Now there's a big gap - use x to jump and X to glide. Do it again. Go onto translocator - you're back at the vendor.
Note if you ride the rails you get to the platinum bolt vendor! Also past the double jump on little platforms go straight and down ladder for bolt - that's before going right down to circle entrance.
There's also a skill point here - Destroy all Breakables. Just destroy things you see around you. You have to get 100 or so items.
Ratchet and Clank 2 Going Commando Walkthrough