Is there any known way to play coop campaign online?

[Merktality]

I don't see anything in the menu that makes it possible

 

[minijman7]

I know as of now there is not a way to do that. There were people trying to develop coop into the game like Himanshu01, but idk if he is active anymore.

 

[UF ShadowTeddy]

Currently, there is one known way of getting coop to work but it requires a lot of memory poking and a main menu mod.

There a third party apps available which can do this, but they are known to crash the game.
There are also a bunch of bugs and de-sync issues that render coop unplayable and not worth setting it up (such as clients being unable to see their weapons,)
I have been looking at all the campaign maps, to see what works and what doesn't over coop:

1. Cairo - Hit and miss. Sometimes both players spawn, sometimes only the second player's biped spawns (but they aren't 'spawned in'). Not to mention the game crashes as soon as you hit the load trigger zone into the first area
2. Outskirts - Does not work. Same as Cairo, in regards that the second player's biped will spawn but be unable to see anything (That's if you get lucky and spawn both players in after you skip custscenes). There's a bug with the cutscenes wherein after a coop instance is setup on outskirts, the game will keep looping the cutscene
3. Metropolis - Same as above
4. The Arbiter - This indefinitely leads to a crash. I cannot remember why
5. The Oracle - Same as above
6. Delta Halo - Prior to what other people have said, I have gotten Delta Halo to work on a coop instance (with 2 players, host and client) Delta Halo works very well, all scripted events seem to work on client side
7. Regret - Regret works up-to a certain point (Where you need to ride the water elevator in your pursuit for regret, the game will stop registering properly on the client side and drop the client out of the available spawning players)
8. Sacred Icon - has issues, don't remember what
9. Quarantine Zone - should work without any tools as me and PNill were testing out coop on the Quarantine Zone. In the latest release of the Project Cartographer, you should be able to set-up the game without the need for external tools as PNill has implemented some coop hacks in the Xlive.dll
10. Gravemind - Gravemind is an interesting one. Both player bipeds will spawn but the second one will be uncontrollable as the game hasn't registered properly on the client end. If it does, Gravemind could be another good map to coop on (like delta halo) although I imagine it would bug out similarly to Regret
11. Uprising - Uprising works as well as delta halo does over coop
12. The Great Journey - Same as above, except for the final boss fight. The final room will de-sync on the clients end, so a good rule of thumb is to try and get a vehicle like the banshee into the final room (if you want Player 2 to participate in said fight.)

So is it currently worth it to get coop setup as of right now?
Honestly I'd recommend not to. 4 levels only work on coop, That's 40% of the campaign you will be able to enjoy with your buddy over Halo 2 PC (Not to mention the bugs, etc). For now, I guess your just gonna have to wait

 

[Himanshu01]

Well about Coop update
Yes I am working on it And i will provide with a short update that will make things much easier in coop ,(An ingame Console , yes Halo 2's first console)
It will manage most of things like setting respawn and others by itself
Also I will be adding the Revert Checkpoint on Dead

Right now i am finding ways that can make Coop sync much more properly (The teams, Wep Bug, Ai animation /Biped bugs ,etc..)
Hope i am able to complete in a few weeks

So keep playing Folks
:up:

 

[PtolemaiosIV]

dude i can't wait, I expect great things Himanshu, GREAT THINGS.