Rankings

On a ranking list, or leaderboard, each player has a single score that can move up or down depending on his or her performance. If you submit positive values, the score goes up for the player, and if you submit negative values, the score goes down. This score is then the basis for the player's position, the one with the highest score is #1 on the ranking list, the one with the second highest is #2 and so on.

If you make a shooting game, you could have ranking lists for “total kills”, “enemies hit”, or even better “kill/death ratio”. If you make a poker game you could let the ranking score represent “chips”. Whenever someone makes a bet you decrease the score, and whenever someone wins you increase the score. The ranking list would then show which player has the largest stack.

Allow players to compete!

It's fun to play, but it's even more fun to compete. Players can always view the highscore and rankings the way they want to, either all-time champions, or just a list with their friends.