Wiki wrote:
Performance points are heavily based on map difficulty which is determined by a unique algorithm in every gamemode. Based on this difficulty alone each of your scores is rated and assigned a pp value.
Q: Why did I only gain 30pp when the map I played gives 100pp?
PP is a weighted system. This means that your highest pp score gives 100% of its pp, the next one 95% and so on. So your 100pp score may only be weighted around 30%. This does not, however, mean that you actually get a 100% pp gain, even if you set a new personal top performance, as every other score you have will be weighted less than they did before. It's quite easy if you think about it for a little bit:
Let's imagine that your top rank only has 2 maps and looks like this:
#1. 100pp, weighted 100%
#2. 100pp, weighted 95%
Your total pp will then be 100 + 95 = 195pp. If you now set a 110pp score, your top rank will look like this:
#1. 110pp, weighted 100%
#2. 100pp, weighted 95%
#2. 100pp, weighted 90%
As you can see, your new total pp is not 195 + 110 = 315pp, but 110 + 95 + 90 = 295pp.
Let's imagine that your top rank only has 2 maps and looks like this:
#1. 100pp, weighted 100%
#2. 100pp, weighted 95%
Your total pp will then be 100 + 95 = 195pp. If you now set a 110pp score, your top rank will look like this:
#1. 110pp, weighted 100%
#2. 100pp, weighted 95%
#2. 100pp, weighted 90%
As you can see, your new total pp is not 195 + 110 = 315pp, but 110 + 95 + 90 = 295pp.
Q: I used to get some pp from playing 100pp maps, but now I get nothing?
This happens for the same reason as above. At some point, the score will be weighted for 1% or less, and your overall net gain of pp will be so small that it's negligible. Set some scores worth more pp to gain more!
Q: I played a map and I suddenly lost 384495 ranks! Why did I lose so much pp?
Are you absolutely sure you lost pp? Remember that a ranking is dynamic. When you go to bed, countless of people below you will play the game and achieve a higher pp score than you. Your rank does not update until you play a song, so when you play a song, and get to the result screen, it will look like you suddenly lost a lot of ranks. In reality, this most likely happened not because you lost pp, but because other players gained pp, either while you were busy playing the map, or while you were busy doing other things.
Q: I just got a new score on a map, and I lost pp for it. Why isn't the highest pp score saved?
osu! is a fairly old game, and back then, pp didn't exist, and score rankings were the alpha and omega. And while we do have a pp based ranking now, map ranking are still determined by the player with the highest score, and not the highest pp, and therefore you might occasionally lose pp from getting a higher combo with worse accuracy, or playing with HD with worse accuracy or similar.
Q: Why is x mod over-/underweighted? This is wrong!
Almost every "mod specialist" that keep talking about mods being over or underrated falls into either category:
1. Those that think their mod is underrated and the others are overrated (because "if I had x I would totally pp farm that stuff while I'm totally pro.")
2. Those that think their mod is overrated and the others are underrated (because "rofl this is soooooooooooooo easy I'm so good at this game.")
In reality, no system can be completely perfect. Some maps will be easier than others, while still give the same amount of pp, and that's just how it is. Difficulty is also subjective, and it depends heavily on what you as a player specialize in. A HR player might find a particular map overweighted with HR, while a nomod player might find that pp weighed perfectly fine.
1. Those that think their mod is underrated and the others are overrated (because "if I had x I would totally pp farm that stuff while I'm totally pro.")
2. Those that think their mod is overrated and the others are underrated (because "rofl this is soooooooooooooo easy I'm so good at this game.")
In reality, no system can be completely perfect. Some maps will be easier than others, while still give the same amount of pp, and that's just how it is. Difficulty is also subjective, and it depends heavily on what you as a player specialize in. A HR player might find a particular map overweighted with HR, while a nomod player might find that pp weighed perfectly fine.
Q: Why is x map over-/underweighted? This is wrong!
This has more or less the same answer as above. Additionally, the pp algorithm currently does not really take reading difficulty into account. This means that maps that are difficult to read will very often be underweighted compared to their overall difficulty.
Q: How do I get more pp?
Play more.
If there're any other questions and answers that I didn't put here, feel free to post them and I'll add them (probably).