It was previously called Daily Competition. It would randomly choose a flash game (It even chose the retired Earth Faerie Aces game once) that people would play. You would enter the competition by paying a small fee: 10 to 120 NP depending on the hour of the day:
1&2: 10
3&4: 20
5&6: 30
....
23*24: 120
Every time you entered, you would then go and play the game and send score. This score would be sent to the database, and compared to the score of another user, thus determining a winner. Record was kept of the number of wins and losses you had, over the course of one hour.
Timed like this:
2 to 3: enter the contest and play
3 to 3:30: finish up matches
3:30 to 4: ranks determined and prizes rewarded.
The previous beta of this took your money like it was supposed to... but didn't reward people for their wins...
I think that explains most of it...