I'm with AmiDude on this one; I see no point in upgrading to Kickstart 3.1 either, unless the current Kickstart ROM is below rev. 37.350.
It might be cheap to obtain a Kickstart 3.1, but if the aim is just to play games, why bother? You would just have paid money for features that you don't need. For almost the same amount you can register WHDLoad instead; as I see it that's money better spent there.