@Clint_L is right about one hour being a tight window.I've run simple systems before, but how simple do you think I could go and still have it be fun and meaningful? Three ability scores, d20s for attacks and skills, d6s for damage?
That sounds like at least 3 hours to me, even for some prior role-players.I'd try to fit in one bit of role-playing, one bit of exploring, one fight, and one puzzle. It would be neat if I could have at least a rudimentary sort of character creation where they got maybe 3 choices, and could pick from four options for each, ideally with cool illustrations.
You want something stripped-down that conveys the idea of rolling dice for outcomes, like this:This is all very tentative now. Does anyone know a really easy system to use? Should I use something geared for kids like No Thank You, Evil? Or should I write one?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.