Tomb Raider 4: The Last Revelation

In training level, after crawling through the grate to open a door (and find the backpack), when crawling back out turn right and crawl toward the second grate. There is another skull there.

Make sure Lara is facing EXACTLY North on the compass
Go into INVENTORY
The needle on Compass should be transparent - if not, you are NOT facing exactly North.
Select the Large Medi-Pack
Hold L1, L2, R1, R2 and Up, then press Triangle
You should have all Weapons now

Turns laras pistol into a nuclear missile launcher. During the time when its loading the title screen enter L1, L1, L1, Triangle, Circle, Circle, X, X, X, X, R1, R1, R2, L2, Square after that you have to get to the second level and pick up the shotgun ammo in the tomb when you dont have a shotgun then go to your inventory and click on the shotgun ammo and it will be your pistol and then press L1, L1, L1, L2, L2, L2, L2, L2, R1, R1, R1, R1, R1, R2, R2, R2 then put it away and take it out again. It will then shoot nucuelar missles

In the begining when you play as Lara the teen. In the very begining walk to your left go a little up and you should find a golden skull. When he is teaching you how to make the running jump automatically fall go to the back and you should get another skull.

Here is an easy way to make sure Lara is facing EXACTLY North...
Find any block that faces North
Vault on to it
Go into INVENTORY
The Compass Needle should now be transparent!