Hi; that sounds as you'd be descriving an object which makes the "context". In this case it is essential to know it. Besides, as "water proof" means that that object can't be damaged by water, "tilt proof" might mean: -- 1) that the object can be reversed up and down, and it still works well (eg. kamasutra) -- 2) that the object cannot be tilted -- no one can accidentally hit it and change its inclination (eg. a strong wind) Only the specific kind of object would define whether it's the case of 1. or 2. PS -- It also seems, it may be a derived metaphore used to describe a person with a very calm/ firm attitude toward problems. I guess that's the real topic of your question?

What kind of game? (that actually matters for this question)