We use games on electronic devices as a way of enabling our boys to have fun while learning. They are younger than yours, but we use the following that they are free to choose from whenever they want "screen time" (in no order of preference)
- Leapfrog Explorer with various games (all set to at least 2 years above their actual age)
- Mathletics (online maths program including live time rounds for mental maths)
- Timez Attack (this is the current big favourite for both of them)
- then the usual Jump start and reader rabbit series that they can choose from at will
- a variety of websites that they can browse that cover topical information.
The way I see it, as long as they are still content to play, do sports and are well rounded as you indicate, I really do not see a problem with it. When I feel that they have been on too long I chase them off to go play outside or whatever. Or I set up an activity like baking or crafts or science exploration and experiments. Usually they are aware of what is happening around them and quickly come to see what I am doing.
It's also the way of the future, regardless of how we may not want to accept that - the whole technology thing.
But because they are still learning to self-regulate this sort of thing, we limit them to about 45 minutes at a time, and then at least a 2 - 3 hour break. We also have no screen time after 5pm when its dinner and bath and relaxing time.