A purpose built games room seems the best option on 1 level, most new homes have a media room which is far too small!!

A 140m2 minimum required, great value add in my professional opinion.

I have valued some mcmansions in recent times and most these homes have huge rumpus/family areas.

If I was building again I would have a 3 - 4 car garage that's 8.0 mtrs deep plus a rumpus area that backs onto the garage.