Don't just identify places vacuumed vs not, but include places vacuumed multiple times. Provide a score. Goal is a perfect 0, negative score implies missed areas, positive is over-vacuumed... Positive score only counted if the whole area is vacuumed to avoid just cleaning the same tiny area until the over-vacuum score counts for the whole rug.

Now, make this an AR game, with leaderboards based on rug dimensions.