I said I was going to make mah gam, and now I'm going to have to stick to my word. I read a Tim Rogers' Kotaku post that talked about, among many other things, how to make a 'proper' sumo wrestling game. Here's the quote:
The third would be a minimalist take, with Pong graphics: two paddles start face-to-face inside a square arena, several blocks apart. The player can move his paddle left or right, pressing one of two buttons to fire one of his two projectiles (representing his left and right hands). The projectiles fly forward. If the projectile hits the opponent, the opponent is pushed backward. If a projectile hits the wall behind the opponent, it bounces toward the back side of the opponent. If it hits him then, it pushes him one square forward. If the projectile misses the opponent, it continues toward the player who fired it. Now he has to dodge his own projectile as it comes back. If he dodges it, it will hit the wall behind him. If he lines himself up and takes a hit in the back, it'll move him forward. This is the only way for a player to move forward, regaining ground. If the bullet misses him after its second bounce, it continues toward the opponent again. If it hits, the player is pushed back. If it misses, it touches the back wall and disappears. The player can only have two active projectiles on the board at a time. Projectiles will all be the same color (white, on a black background). A ghosty trail behind the projectile makes it easy to understand which direction the projectile is heading. The key thing to note here is that, outside of the exact instant the projectile is fired, the player can neither tell nor care which projectiles on the field are his: the only important thing is knowing which way the projectiles are moving, and what to do about or with them (try to be hit from behind while avoiding hits from the front). If your paddle moves forward past the center line of the playing field, the opposing player will be pushed backward so as to maintain the minimum distance ("minimum" in so much as if you were too close to the other player, it wouldn't be fun anymore). Any player pushed back to the line behind his back will "fall out" of the ring, losing the match.
This sounds easy enough, I imagine I shouldn't flub this up that badly. I'll see how this goes before I go and attempt my own idea.