So I was playing Tomb Raider: Anniversary the other day and I finally beat the whole Peru stage. Beating stages in this game will unlock things (and there's a ton of stuff to be unlocked) including commentary for the level you've just beaten. Once you've unlocked commentary, you can just replay the level (which you might sometimes need to do if you've missed hidden secrets, artifacts etc) and there will be these purple markers that you activate in the stage which will play commentary from the creator of the series and the creative director of Aniversary, who'll talk about different things like how they updated the level you're on from the original game, the different puzzles of the stages, etc. It's like a DVD commentary in other words, and it's pretty fascinating. 
Just thought I'd point out what a cool feature this is. I really hope other companies pick up on this (I'd love commentary for games in the Final Fantasy and Zelda series, for example).
Just thought I'd point out what a cool feature this is. I really hope other companies pick up on this (I'd love commentary for games in the Final Fantasy and Zelda series, for example).