The NP ratio tells you how many Neopoints you'll earn for every point you score while playing a game.
For example, if the NP ratio is 100 NP for every 150 game points scored, to earn the maximum 1,000 NP reward for playing, you'd have to score 1,500 points during the game.
On the other hand, if a game's NP ratio is 25 NP for every point scored, you'd only have to earn 40 points in the game to get the full 1,000 NP for playing.
Carnival of Terror:
There once was a carnival so amazing that Neopians from all around would flock in droves to see it. Visitors were enchanted by the carnival's colourful shows and spectacular attractions. The fun came to an end, though, on the day that the nefarious Dr. Sloth sent an invasion of robot Chia clowns to take over the carnival and then use it to capture all of Neopia! They’ve already infiltrated the once joyful carnival, but with your help, their reign of mechanised terror can come to an end!