The Skillz multiplayer system assigns a skill rating for every player. As you play the game, the system changes your skill rating based on the opponents you face and the scores you achieve. When you win games, your skill rating will go up. When you lose games, your skill rating will go down.
When you enter into a new match, the system looks for other players that are close to your skill rating and does one of two thing.
If there are players close to your skill rating that have already started a match, you will be given the same match as them.
If there are no games available from players close to your skill rating, you will begin a match that will later be picked up by a player close to your skill rating.
In both of these cases, the matches are always played by real players. If no player close to your skill rating is found to match your game within 24 hours, then your entry fee will be refunded and the match canceled.