Years ago Zynga asked me how would I design a vending machine for blind people which was annoying because I asked it immediately back and clearly they hadn't even thought about it themselves. But then I brought up Ian Bogost and it was a hard stop basically, lol.

edit: Is it health? Like health tracking / indication? Not all games require it but maybe in the right context this would be the most important. This is snarky but I think you could run with it (health being the most important "number").

response to your edit: Your interpretation of the question makes a little more sense. He was talking about a specific number, not a concept\variable that is common in games. For Zynga I'd probably say energy or money or something, although any tracked resource that determines loss, victory or progression would work for your version.

Edit: doing any "technical" work prior to doing research is a display of technical INcompetence.

Who is this “we”?

If I ask you "How can you attempt to get the answer to this in under a minute" or "what's the first thing you would do" and you don't say "search for existing solution" (it doesn't have to be Google), you fail. You don't have to read my mind; I want to know where YOUR mind goes first. And if it goes to anything more complicated than "I'll try to look it up" you just simply fail; I can't afford to have you wasting any more of my business' time.