My first introduction to Torchbearer was this article.
The key paragraphs for me read as follows:
Actually, Torchbearer is a pretty excellent description of what the new game is all about: resource management in the dark depths of “improbable ruins.”
Each torch you carry burns out in a set length of time. Each flask of lantern oil takes up precious space in your pack.
On the character sheet, both your hands are accounted for. What each hand is holding is marked down. Every tiny detail of your encumbrance, from the food in your pack to the shield on your arm, is an important factor in determining your character’s survival.
In other words, "How deep can you go before you can't come back?" Or "At what point does the possibility of treasure outweigh the difficulty of escape?"