Bukkit

Your config.yml SHOULD be blank when you first download the plugin

Here is a default config. Feel free to copy and paste it into your server or just use it as a guide

Coal:

playingtime: 40

command: give <player> 1 20

Iron:

playingtime: 60

command: time set 0

Gold:

playingtime: 80

command: tell <player> You have just played for 80 minutes!

Remember You can't do more than one command and also this does not auto rank your players to rank them up you must put the command that would such as the rank below would rank the player to group diamond after 100 minutes IT IS THE ONLY RANK IN THE CONFIG THAT RANKS THE PERSON UP!

Diamond:

playingtime: 100

command: pex user <player> group set Diamond

This is the pex command to rank someone up and I believe that all permissions systems have an in game player rank up command such as this