If your thinking as using at specific game as a teaching tool, you would have to pray about it. God gave me a teaching lesson on fear using SpongeBob SquarePants. So I'm sure that if it was His desire he would give you one about a specific game. I think that using the game console itself is a great way to invite people over to hangout and then pray that God opens a door to share the Gospel with them. Of course you would want to play only spiritually appropriate games (nothing taht is going to grieve the Holy Spirit).
Last night as a matter of fact my mother came over to play Zelda Twilight (yes, I said my mother). There was this part where Zant (a bad character) was speaking about how he became evil. He spoke about how he contacted a god. It was at that point that we paused the game and we talked about the differance between God and gods. We also talked about things that we could turn into gods and serve like TV, Food and Video Games. Then we continued on with the game.
So yes I think that you can use video games/systems as a way to spread the gospel.
Just as a side note. Every time we play Zelda Twilight my son sings a song by Shaun Groves called Twilight:
Like the sky before the dawn
While the night is holding on
Sun and moon together in the gray
So my soul is shared by two
The worst of me, the best of You
Saint and sinner mingle in my veins
And I pray You'll end this twilight
(chorus)
Twilight, twilight
I'm torn inside my soul tonight
The dawning Day, the dying night
Oh rid my soul of twilight
Oh rid my soul of twilight
Good I love but evil's done
Good intentions come undone
Good to know I know the One
Who saves me from myself and
(chorus)
Oh Lord, paint my heart a solid hue
The shade of You
Oh Lord, break this dreadful in between
inside of me
Oh let it be morning
(chorus)
I know the Son is coming up
Oh, the Son is coming up
Yes, the Son is coming up
In me, in me