Of course, this doesn't really fit in with normal OFP missions. But if one succeeds in making a really nice chess mission I think that it can be a good map. But it looks really hard to me, to make it work properly and enjoyable.
Definitely worth attention, but should be well though over.
The first thing is if you want only chess play, or you want a cutscene when a fight takes place and the winner wins. Don't think that it'll be playable then. Imagine a pawn (soldier?) vs the queen, pretty fair ugh
An idea is that you let them fight and the winner wins, even a pawn can win against the queen. Given that the pawn is a LAW soldier. After the fight you don't setDammage back to 0, but let it keep it's injuries etc. This might make for a interesting mission.
But of course, the problem remains, it will be quite hard to make. And even harder to make it playable properly. And the hardest part would be to make the mission more fun than standard missions in my opinion that is.