Concept: "QWOP" is a ragdoll-based game where the player has to control an athlete using only the q, w, o and p keys. In this magic game, the player would have to control the left and right fingers of a magician in order to perform an effect.
You'd need 4 keys for each hand, so you can control direction. But you also need some for actions like "pressing", "grabbing".
You need 10 keys, 5 for each finger.
The game could alter between a set of keys for the movement of the hands and one for the movement of each particular finger.
The effect that must be completed can be as simple as the first phase of an "Ambitious Card", where a double lift is executed, turned back face down, then top "X" card inserted in the middle, a wave of the hand over the deck and a final reveal to finish the game.
OR
QWOP x Building House Cards
With w,a,s,d you control direction and with "c" you grab and release a card (left hand).
With j,i,l,k you control direction and with "n" you grab and release a card (right hand).
The goal of the game is to build as big of a card house as possible, every card having a certain point value.
Much simpler in comparison with the other one. But it depends on what you want to achieve.
Notes:
It doesn't have to be a video game. It can be an animation sketch, a snippet of what someone in a movie is playing, the game could be described in text if you are to write a game story. It's up to you how you use this knowledge, but don't forget - don't take it as it is, mold it, play with it, digest it and then give birth to something that is uniquely you.