Tomb Raider: Legend

Story Related and cannot be missed

Will unlock after completing the final level. It's a really short level and only Involves a boss fight. Look in the spoiler for more info on the best way to beat the boss. If you want a super easy way to do this level then see this thread:

Final boss advice on hard mode - a quick guide to all those unanswered questions

The final level is back in Bolivia, you only have to fight the thing (Amanda). You get to use the sword and it's pretty simple, however on hard it's brutal.

First of all you have to take out all the enemies on the round platform, use the sword. Now kill all but 1 enemy; now go around and pick up all the available health packs. You will now have them for the final fight. Kill the last few enemies to trigger a cutscene.

You now have to kill that weird thing. You have to make sure you don't get hit by it as it deals loads of damage. Make sure you don't get any splash damage from the sword as this hurts you. When you have hurt the thing enough it will fall to the floor, you now must go up to it and press repeat this 4 times and on the 4th time it will die.

Consult the video listed under have a good time all the time for a walkthrough. See The Hard Way