Here's a zip file with every Blocker updated. (low and high res)

This is all ten included in the latest Styles package. Lemmina, Croft, Orig, Xmas and the black honeycomb Lemmina.

Here's the first one done.

I like the idea of the exits locked after time is up.

One more possibility would be to play the old Failed end-time jingle after the time is up. This would be very clear something negative happened. I liked the old jingles, but they seemed to me that they should have been accompanied with a lemming with his thumb up or something like Revolutions... and a sad face for losing.

I like all the other ideas.

disallowing OWF blockers fixes this as well, right?

About the blockers getting ignored in one-way zones...

Could you just disallow blockers in these zones? Make the selecting tone (or a fail tone) but not reduce the amount of available blockers?
This would (I think) have a better look and feel.

I don't know if this is intended or not, but the new release rate tone doesn't play when paused. It seems like it should have sound since it allows you to adjust the rate.

One last attachment.

I didn't find 2x speed to be fast enough so I edited it again to be 4x.

Here's my edited icon pack.

I added a yellow outline to (skill select) so I can see what's selected better.
I used the bigger lemm95 icons for + and - adjusted to match existing colors.
I used the lemm95 pause. It's easier for me to see as well.
And the tweaked Nuke button that is similar but shaded better.