What is the point in this?
We've all played osu! offline at some point. Whether it is you have no internet in your home or you were trying to get your Wi-Fi extender working. Anyway, we should be able to enjoy the fun of gaining pp, but be able to enjoy it without a connection. This may also be great for times when you are out and about with a Windows tablet and no WiFi to use, but you still want to gain some pp.
How would this work?
Simple! Keep the pp engine working while offline and store the number in a log that will be stored. A .txt would work well here.
Will it still be the same as online?
Absolutely. In fact, it'll be the same algorithm used. You can even view your top offline plays. Sadly, loved maps will never gain local pp.