what would be the means to explore concepts etc. specific and exclusive to video games?
This seems to be a question about the form. I've blogged about my take on
what makes videogames distinct, you might be interested in checking that out.
My conclusion was that formal distinctions in media are based on technology. And that if you want to explore a concept exclusive to videogames, you should explore something that you can't through other media.
So I think that could involve a number of things. Interactivity, as you mentioned, would be one. But that doesn't have to be the only one. The other could be procedurality - the calculating of some sort of simulation. In fact, in some ways, that is a more primal characteristic of computers, since the first one was used for calculating projectile trajectories. The most timely concept to explore would probably be interaction between people on the Internet.
In terms of content, I really like how Michaël describes the medium of videogames as a medium of
being. If oral tradition gives you telling, and cinema gives you showing, videogames give you being. So content-wise, you could try to create an experience that gives you a sense of being.