One of the best multiplayer games of its generation. Smooth, varied gameplay, great performance on a PS3, and active community servers on weekends. The game also has one of the best implementations of split screen that I've ever seen (ex. https://youtu.be/KvzjWt2H8WQ?t=91). Buying a new copy is also dirt cheap nowadays.
Having no offline offerings is a obvious minus, though.

Multiplayer info here: https://www.psone.online/home

Everything about this game is so cool. The settings, the gameplay, the world, the soundtrack, the vehicles, and the really big knives. My biggest complaint is that it's multi-player only and has no story or other single player mode. All the makings of a great story are there, almost as though they wanted to make a story and just didn't have time.