The Tree House

It is a bonus which is available after you have aquired 25 skill points, or
If you set the psp clock to 3:00 A.M. And go to the metalis arena. hope I helped.

The treehouse is like a museum for Ratchet and Clank. It has different floors, each containing some special places of interest.
GUIDE
OUTSIDE OF TREEHOUSE: You will see a statue of ratchet with his omniwrench 10k.You will also see some birds, called Birdadactyls.Sadly, these fellas weren`t put in the game.Then, you will see a couple of sketches of multiplayer skins that didn`t make it into the game.(NOTE: there are also some breakable chairs outside of the treehouse)
1st FLOOR: You will see some sketches.(listing them all would take too much time)
LOBBY: As usual, there are sketches.However, there is a TV.You can play some clank challenges there.(All of them earn you 10,000 bolts)
2nd FLOOR: First, you will see a clone.You can make it do different things.IT WILL NOT ATTACK YOU.There is a balcony in which there are 2 breakable chairs.Yes, there are sketches.There is also a 2nd balcony, with a bulldozer on it.You can also make it do different things.Then, you will obtain a weapon called the CUT.It was booted out of the game because its effects were too similar to the beehive`s.You can test it out, but you can`t take it with you.To get to the third floor, there is a ladder.
3rd FLOOR: On the third floor, there is a grind lock on the balcony.Nothing will happen if you complete it.There are also some sketches.
Having trouble finding the treehouse?First, get all the skill points.Then, activate the CLIMB THE TREEHOUSE cheat.It will automatically take you to the treehouse.To hard?Here`s the easy way to do it without ANY skill points:
1. Go to OPTIONS on your PSP`s menu.Change the time to 2:42 AM.
2. Go to ratchet and clank.Fly to metalis.If you`re already there, good!
3. Go to the arena.Note: if you haven`t got the teleporter that teleports you, well, you`re not going to make it!Once you`re there, you will see a new teleporter.It will take you to the treehouse.
IMPORTANT NOTE: YOU MUST ARRIVE THERE BEFORE 2:47 OR ELSE THE TELEPORTER WON`T BE THERE!!!!
Hope my guide helped!

To get to the tree house without any cheat codes go to metalis when you have got the polorizer then use your polorizer and open the large gate which looks like a vent in front of you now complete the planet till you reach a place which had a lot crates there will be one teleporter use it it will teleport you to your ship then save the game and close it set your psp timer to 2.42 am 2 hours and 42 minutes now run the game again and load it use the teleporter you and will be teleported back to the crates and the then there will be two teleporters use the next teleporter and you will be at the tree house (NOTE!!!. AFTER YOU HAVE SET YOUR PSP TIMER T0 2.42 AM GO TO THE CRATES BEFORE 2.47 AM OTHERWISE THE NEXT TELEPORTER WON'T APPEAR!!!)

AFTER you GET you're SHIP GO TO JUNKYARD WITH POLARISER,BEHIND you're SHIP IS A GRID IN THE WALL USE POLARISER TO OPEN IT GO THROUGH THE REALLY HARD LEVEL,you WILL SEE A LOT OF BOXES WITH A TITANIUM BOLT TAKE THE TELEPORTER TO RETURN TO SHIP AT 2:42PM GO TO THE AREA WITH BOXES you WILL SEE A LIGHT FLASH TELEPORT TO REACH THE TREEHOUSE