Handstand:
To do a handstand when you climb an object, hold Walk as you climb.

Somersault:
To do a somersault, crawl to the very edge of a platform or ledge. While holding Crawl, press Jump. Lara will somersault into the area below. This is better than having to turn around and climb down while getting out of a tunnel. This is also useful when getting into the water mill in the "Old Mill" level.

Air Flip:
Instead of jumping forward or backward and pressing Roll immediately, press the opposite direction. For example, if you jump forward, immediately press Down and Lara will do a flip in the air. Do the opposite if you jump backwards.

Roll easy:
To roll easily, instead of pressing (End) press the [Up] + [Down].

Snap Lara's neck:
Do a somersault jump (Jump while pressing Walk forward) from a high place. A good place to try this is in the very first Streets of Rome level, when you are above the awning. If you attempt to do a somersault jump from above onto the awning, she will dive head first and snap her neck when she lands on the awning, causing the game to end.

Unlimited Large Medipacks:
Note: This code will only work when your health is not full, and you have exactly one Large Medipack. Press [Esc] to open the inventory screen. Highlight the Large Medipack, then hold [Look] ([Keypad 0] by default) and press 9 on the top row of the keyboard. Then, use the Large Medipack once. Exit and re-enter the inventory and you should have unlimited Large Medipacks.

Unlimited Small Medipacks:
Note: This code will only work when your health is not full, and you have exactly one Small Medipack. Press [Esc] to open the inventory screen. Highlight the Small Medipack, then hold [Look] ([Keypad 0] by default) and press 0 on the top row of the keyboard. Then, use the Small Medipack once. Exit and re-enter the inventory and you should have unlimited Small Medipacks.