This script ranks comments on Hacker News by the time since someone last responded to it or a descendant, like in old forums.

It completely ignores votes. If you respond to an old comment, you'll bring the entire tree to the top. If two comment trees are equally old, the following algorithm adapted from https://news.ycombinator.com/item?id=1781417 is used as a tiebreaker:

gravity = 1.8;
timeBase = 120; # 2 hours
return 1.0 / (age_in_minutes + timeBase) ** gravity;

For old threads where all comments are equally old, this converges to "most replies first".

In a future version, the following features may be added:

• Sort the frontpage by comments/engagement too
• Automatically upvote comments you respond to