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.
Magma Blaster:
Oh no! A volcano is erupting, and some Tyrannian Neopets need your help in order to escape the lava and rocks that are raining down on them. Use your laser to blast the rocks, but be sure to match your laser to the rock type first. If a boulder should crash too near one of the Tyrannians, you'll both be in trouble!