A count down?

I’m trying to make a timer that will count down to a meteor strike, and have the time left display in the status line. The code I have is this:

the meteor strikes in 13 minutes from now; now the right hand status line is "[13 minutes minus the time of day]";
(inside an Instead rule for the activator)

But it just returns in the status line.

I’ve tried several different things, and this is the only one that compiles. Any tips?

[code]The time to strike is a number that varies. The time to strike is 14.

meteor-incoming is a truth-state that varies. meteor-incoming is false.

Every turn when meteor-incoming is true:
now time to strike is time to strike - 1;
and when you want to set the timer:

now meteor-incoming is true;
now the right hand status line is "[time to strike]";

(Or you can do it with time instead of number.)

You can also phrase it like this.

decrement the time to strike;

Hope this helps.

Thank you so much!