Just what I need for my next mod. Thanks!
I'm curious if there is a reason you didn't include:
if countdownRunning then
startLuaCoroutine(self, "countdown_routine")
end
in the onLoad function. Rewinding time or otherwise loading the game while it's running seems to break the timer. I put it in mine, and it seems to do the trick, but I'm worried that you left it out for a reason I'm not seeing yet.