The modder who added seamless co-op to Elden Ring just launched an Armored Core 6 co-op mod for up to 6 players, and it even adds PvP invasions

Extremely cool not-an-April-Fool's-joke news alert: Armored Core 6 is co-op now.

I loved the mech combat in Armored Core 6 when I reviewed it last year, and it was a strong enough singleplayer action game to run away with our best action game of the year award, just like Sekiro: Shadows Die Twice in 2019. It was just a bit disappointing, though, that I couldn't play Armored Core in co-op, the way I'd battled through all of FromSoftware's Dark Souls games and big chunks of Elden Ring. If only there was a modder out there who could make such a thing possible—maybe even a modder who already had experience with turning Elden Ring into a proper front-to-back co-op experience? 

Yes, dreams do come true—after teasing Armored Core 6 co-op back in November, modder LukeYui launched an alpha version of the mod on Sunday, enabling co-op play for up to six total players in a match. The mod also enables classic Souls-style PvP invasions, so while you're cruising through missions with your co-op crew up to two invading ACs may arrive to try to slow you down. 

The invasion mechanic is actually a fantastic fit for Armored Core, since at various points in the game's campaign—extremely minor spoilers here—powerful ACs will suddenly arrive to make a mission much harder than you may have expected it to be. I have to imagine other players will make for even tougher match-ups than those surprise boss fights. If you hate the Souls invasion mechanic, though, it's still possible to play this co-op mod without it by modifying one of the mod files. As detailed by LukeYui on Nexusmods: 

You can disable PvP in the "ac6_coop_settings" file by changing "allow_evil_guest = 1" to "allow_evil_guest = 0". This option only matters for the host of the session.

Some other details from the mod page: 

• Progression is shared, not just for the host
• The mod works with an existing save file
• The number of invaders scales to party size: you can get one invader solo or with one co-op partner, two invaders with 3-4 total co-op players, and one invader with five total co-op players (six is the max size for a session)
• "To attempt to preserve some of the game's challenge a small amount of enemy health and armour increases have been added to enemies per additional player"
• Using the mod launcher, AC6 does not enable Easy Anti-Cheat or connect to FromSoftware's matchmaking servers, so it shouldn't net you an online ban
• The Ice Worm mission doesn't currently work in co-op
• If you die in a mission, you spectate until your party reaches a checkpoint, at which point you can respawn. A full party wipe requires a mission restart

Installing the mod is as simple as unzipping a file in Armored Core 6's Steam install folder. It adds a new "Squad" menu to the garage, as well as a "Break in Mission" menu option for invasions. To use an existing save file, however, you'll need to do the following before starting up the mod's dedicated executable: 

• Go to AppData\Roaming\ArmoredCore6\[bunchofnumbers]
• Duplicate your AC60000.sl2 file
• Rename the duplicate's file extension to .co2

I installed the mod and gave it a shot with associate editor Tyler Colp, and it worked impressively well for an alpha. You can use your Steam friends list to invite someone to your party, then launch a campaign mission or pick any previously finished mission from the replay menu, and it just works. We ran into one bug where a mission objective failed to advance, but after a quick restart of the mission it worked fine the second time—I'm not even entirely sure that was the fault of the mod, since I hit the rare bug in AC6 back in my solo playthrough.

We were immediately invaded as soon as we started our first mission, implying there are some mod players out there hungry for PvP action. After disabling PvP for the sake of capturing a few minutes of video, we took on AC6's first big boss in co-op. Here's how the mission played out.