The author builds on arguments he has made elsewhere that good commercial video games foster deep learning and problem solving and that such games in fact promote mastery as a form of play. Here he maintains that some good video games engage players with an important type of play, namely of play as discovery, of play as surmising new possibilities in a given environment. The game "Portal" exemplifies this form of play, a form designed to give players a smart tool that enables them to see these new possibilities and use them in innovative ways. The author concludes with a discussion beyond games of young people using smart tools to become Pro-Ams, that is, amateur experts at something for which they have developed a passion.