Ad-Hoc Multiplayer
What is it?
Ad-Hoc, in PSP parlance, refers to local WiFi networks created by PSP systems, for local multiplayer in the room.
Nowadays, this isn't used much in the original sense, but in PPSSPP, we can redirect this type of multiplayer over Internet, providing multiplayer functionality for games that don't support (or don't have revived servers for) Infrastructure Mode.
There are some issues with this though, as you will see when you read the guide, but in many games it can be made to work reasonably well.
How to play
See this page: Ad-Hoc PPSSPP multiplayer guide (which later will be moved here).
Server list
See Ad-Hoc servers.