The only drawback to the first stress test: The battery lasts - if you organizing a long evening - very limited before the first signs of fatigue (slower pace, less changes) are noticeable. Since a good 9-volt block is not exactly cheap, which can quickly go to the money if the game is more commonly used; at the same time refuse to discount batteries much faster, so the game can only be guaranteed with proper brands ...
Personally, I have decided to prepare this disadvantage by fitting a transformer to an end. Our version is so naturally definitely "not toys" more; but we also have other interests, if we build the game ... :-)
In short: Anyone who wants to spice up the game, it's no wonder. For now and then the 9-volt batteries are entirely sufficient, and I see no reason why not the little one (perhaps under supervision) should also like!