The PlayStation 3 emulator now supports online matchmaking for some 2000s greats, including Armored Core 4, Ridge Racer 7 and Tekken 5

pcgamer.com:

PS3 emulator RPCS3 is a wonder: it's able to at least boot the whole PS3 library, taming the notoriously complex Cell processor to make PlayStation 3 games playable on any modern PC. Its emulation even extends to online play for certain games playable via PSN, and that functionality just got a boost this week with a new update, with support for FromSoftware's Armored Core 4 and Armored Core: For Answer, racing games Ridge Racer 7 and Wangan Midnight, fighter Tekken 5, and more.

While some of these games like Armored Core were previously playable with some custom workarounds, this new update for RPCS3 makes them playable via emulation of PSN's matchmaking service, simplifying the process of getting into a game. RPCS3 has a companion service called RPCN, which is «an open-source server that emulates the P2P match-making done on the PlayStation 3.» RPCN 1.3, released yesterday, adds a number of PSN functions that some games used in their matchmaking implementations. With that, they've now become playable. 

Here's a list of newly confirmed supported games from the RPCS3 Discord, though there are likely others that work now as well: 

In the Github notes for this update, developer RipleyTom noted that they also fixed server implementations for all of Arc System Works' PS3 fighting games, which includes Persona 4 Arena and multiple BlazBlues. Soul Calibur 5 and King of Fighters 13 should now work, too.

This update essentially only applies to games that used older versions of PSN's player-matching APIs. There are plenty of games already playable in the emulator via netplay, and there are others that still won't work because they used their own unique implementation. For those, online play is only going to work if someone reverse-engineers the original code to create a custom server. While that's a great deal of effort, it's certainly possible. Metal Gear Solid 4's online component, MGO2, has had custom PC servers since 2021.

RPCN emulates PSN's basic matchmaking system, but