String is also weirdly difficult to obtain underground.
The most plentiful and straightforward source is “Hide Straps” from the skins of various fauna, however you need String to dry the hides in the first place. The only string feasibly obtainable without first getting string from the surface is “Tough Roots” from tree stumps, but stumped trees only occur on levels 3(?) and below, certainly not on L1. Guess what material you need for the ropes to reach L2+ via minehole?
Caves need more sources of String. There are a few possibilities:
- 1. Add a forageable string. Could even make “Lamp Stalks” count as string since they’re otherwise pretty useless
- 2. Add “Tough Bark” to at least one underground tree. Moundtrees, perhaps? Ideally it would be a tree available on L1 but that would require a world reset to put a tree in L1 naturally.
- 3. Give Rats (either/both sizes) an uncommonly-dropped Rat Tail that works as string.
I’m making these suggestions not to add random mishmash content to caves but because I’m interested in a “Caves Only” type of challenge and these limitations are impossible (in the case of Boughs) and practically impossible (in the case of string, yes I know about Troll hairs) to overcome.