It seems like the first thing they might want to work on is the timer. Here’s a link to a previous post in the forum on how to create a countdown timer in GameLab.
Then, instead of a message that says “time’s up”, they could have a sprite show up (either by making an invisible sprite visible or by moving a sprite that’s off the screen somewhere to the location of the minion.
Hope this helps. If they start making it and run into problems, let us know and we are happy to look at it.
Mike