>Is there not any kind of rule that when an arcade game reaches say 10yrs old it can be >emulated or try to be emulated? It would be nice if it is.
As posted in the past by some MAMEdevs in past years (some posts are archived on MW and probably still could be found on MW forum if doing back searches), there isn't any time frame rule. The one rule that could be considered is if a newly released product that a company is still marketing is earning lots of money, then don't expect specific game to be emulated in MAME.