It should be something like: 1-8, play card in hand, 0 all pillars. Let's say that we play a Lightning, you then press shift to target your opponent's cards or he himself, shift again to target you. When you activate an effect that targets something (lightning, again), letters appear on the valid targets of the selected field. With 26 letters it'll be more than enough to target your opponent's creatures and him.
I don't know about how difficult it'd be to program, probably not too much, but not too little, for sure.