Reddit reviews This Time of Darkness

I think I found it:

I typed "young adult novel sci fi underground" into Google. Second link was
to this
page,
which led to This Time of
Darkness, and I'm 95% sure this is it.


Edit: Now I'm 100% sure. Google books has it online. Here's the page about the rats

This is This Time of Darkness

https://www.amazon.com/This-Time-Darkness-H-Hoover/dp/0765345676

• Little Brother by Cory Doctorow (free ebook version published under Creative Commons license).
  
  
• Ready Player One by Ernest Cline, although it is written to hit a nerve with those who remember the 80's I'd still classify it as "Young-Adult" (or maybe Young-Adult for Adults).
  
  
• This Time of Darkness by H.M. Hoover. A dystopian tale of 2 kids trying to escape from an underground city to freedom, although maybe aimed towards readers younger than YA.

Perhaps This Time of Darkness?

Is it This Time of Darkness