The problem with most multiplayer games on iOS is that even many well-realized multiplayer components are still secondary experiences. This makes finding players extremely difficult. Soccer Showdown goes around this problem in the most obvious way: by making the multiplayer mode the core game mode. This makes it easy to find players to play with, as the only players playing are playing the multiplayer mode. See? Easy.
The game takes the most controversial way to settle soccer matches, penalty kicks, and turns the conflict into a game. Players alternate between the shooter and goal-keeper. The goal is obviously to get the ball in the goal when shooting it, and keeping the ball out when in goal. This is all done against an online opponent via Game Center matchmaking.