I would say 2006's Bully was like Grand Theft Auto for kids if we weren't all playing GTA as kids anyway. Even so, this private school sandbox from the days when Rockstar actually put out more than one game a decade has held onto an enduring fan base over the years — enduring enough, evidently, to make it the latest recipient of the recent online co-op mod trend.
Metal Gear Solid V got one, Tears of the Kingdom got one, and now it's Bully's turn. Bully Online will let you revisit Bullworth Academy with a friend (or several), engaging in everything but the actual main story missions (but with a hefty helping of new content to boot).
The only caveat? The mod comes with an asking price of eight dollars. It may not sound like a lot, but charging any amount of money at all for a fanmade mod is a good way to attract the ire of large companies… especially one as famously litigious as Rockstar's publisher Take-Two. It may be better to enjoy this one as quickly as possible before the inevitable cease and desist.
