If I'm the most recent poster on a topic, it shows as not read. Shouldn't it show as being read if I made the most recent post?

the url changes when you make a post, therefore your browser doesn't think you've read it. blame the browser, not qz ;)
or might just thinking that cause I just woke up.

p.s. when the new forums first went live there was no difference in the link colours

weird. I've never seen a forum work like this before.

Why does it do this? If I put in the old url, it still goes to the same thread with all the posts.

Example:
This first url is from before I read it.
http://www.earthempires.com/...n-life-32136?t=1404236881

This second url is from after I read it. (first and second are exactly the same)
http://www.earthempires.com/...n-life-32136?t=1404236881

This third url is from after I posted to it. It is a different url, but clicking on any of the three takes you to the same topic with all the comments. If it's going to change the url, then I would think that clicking on an old url would show me the topic without the new posts.
http://www.earthempires.com/...n-life-32136?t=1404241844

If the new url doesn't actually change anything, maybe stop it from creating a new url for every post, which would then mark it as read after posting to it.

could be due your browser, FF marks custom govt as read even i'm latest poster.

well, what elves said is true about it creating a new url, which the browser hasn't seen yet, so it says it's new.

It's just weird to me that posting within a thread creates a new url, and why does an old url still work exactly the same as the new url. If they both work the same, what is the purpose of creating a new url?

And I use Chrome. FF used to have a huge memory leak, so I switched.

base url stays same (aka upto ?-mark), only what is after = changes and its irrelevant when posting url.

it should redirect you directly to the post, which should mark it as read

evidently I don't have the redirect url crafted quite right

good catch

It does redirect you, but it doesn't mark it as read.

My last post redirected me to:
http://www.earthempires.com/...rked-as-read-32139#579791

but the new link on the forum was:
http://www.earthempires.com/...s-read-32139?t=1404267034

it bothers you that much?

Yes it does.