I can't think of exactly how I want to word this, but what I'm trying to do is one of 2 things.
First option: Have a set of buttons the player has to buy. Let's say in this case 3 of them. You buy the first one and it makes an button visible that wasn't visible before. Then you buy that one and it makes another button visible and when you buy that one it opens a door.
Second option: Basicially the same as the first, but this time in a random order.
Does anyone know how to do this, I've been trying to do this the last couple of days, but I don't exactly know the best way you excute this, anyone have any ideas?