PC:
UNLIMITED AMMO/GEAR:
Make sure Lara is facing EXACTLY North (An easy way to do this is to climb up on a block, and go to the inventory. If the compass is translucent, then Lara is facing due north). Go to the inventory, highlight the small medi-pack, Press and hold G, U, N, S for a moment, then release. You now have unlimited gear & ammo.
ALL WEAPIONS:
same as unlimited ammo/gear, except the Large medi-pack is highlighted and you hold down W, E, A, P, O, N, S.
SKIP LEVEL:
Make sure Lara is facing EXACTLY North, go to the inventory, highlight LOAD GAME, Press and hold H, E, L, P for a moment, then release and press [ESC]. The level is complete.
PLAYSTATION:
ALL WEAPONS:
Go to the inventory, make sure Lara is facing EXACTLY North, go to the inventory, highlight the Small medi-pack, Press L1 twice, R1 once, and r2 once. press and hold these three buttons, and press up. You now have all weapons.
ALL ITEMS:
Same as all weapons, except that you highlight the Large medi-pack and press down at the end.