Keeping in mind it's the teaching that counts, this is a list of factors I use to evaluate educational potential in games: 1) The game has an educationally-accessible context (historical, contemporary, hard science-fiction) 2) Game play has genuinely educationally-accesible content 3) Success depends on intelligent choices and decisions 4) Failure exists and teaches when it happens. It is possible to lose 5) The tutorial is crystal clear, and checks for understanding 6) There are multiple victory conditions 7) The feedback model is short - students can quickly see how a decision effects a larger whole picture 8) The game becomes increasingly challenging and difficult While the above points are important, it's how teachers use a game which makes it educational. A computer game is educational when teachers consistently probe for understanding. Teachers who set up rubrics, or expectations, for understanding. Teachers who encourage students to share their understandings with their classmates.