How to play Binding of Isaac: Repentance online co-op! (No Remote Play, No Lag!)

Before we start this short guide you need Repentance to do this. The new netcode introduced to the game comes with Repentance and the developers hope to continue this project sometime after the Void rework is done. So please be patient, this will be released for real later! But if you are not patient like me, here is how you can play with up to 4 people!

The "How To" of it.

Step 1 : Go to Properties by right clicking on Binding of Isaac Rebirth on Steam. On the launch commands, enter --networktest.
https://steamuserimages-a.akamaihd.net/ugc/1753565334716927651/11958919F451587DA01B54844F11726B25C91B64/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false

Step 2: Go to the options.ini, you need to enable developer console for co-op, sadly this also means no achievements during co-op play for now. The options.ini is in your Documents/My Games/Binding of Isaac Repentance folder. Within the ini file, find "EnableDebugConsole=0" and turn its value to 1.

Step 3: Everyone who will be playing co-op has to do these two steps, [u[ not just the host [/u]. Don't forget to turn off the debug console once you get back to singleplayer as you won't get achievements! Leaving the launch options as is won't make a difference on your progress though, you can keep it.
Step 4: Pick a character and tell all your friends to also pick the characters they want and don't leave the starting room. Just wait there with your friends.

Step 5: The host must now go to debug console by pressing " on keyboard and invite their friends by using the "netstart" command. To "invite" your friends, you have to have their steam IDs. For example, to invite one of your friends all you have to do is type "netstart 83151943410843" and the friend with that steam ID will soon join your game! Now you can play Co-op together! If you want to play with MORE friends, all you have to do is put the other Steam IDs on the same command, just with spaces in between. "netstart 315835193801 1593148013851 13501830135". In two or three seconds, you'll see a screen with four isaacs! Good luck!

Small Things You Have To Keep In Mind

Anyone can play with either keyboards or controllers! No restrictions on this unlike in Remote Play! The game will stutter a few times at the start of the co-op session and lag is compensated with stutters, make sure you have a stable internet connection. You don't need it to be too strong, I can play with my friend from Germany just fine from Turkey. As far as I've tested, the game will Desync if you: Use more console commands OR decide to fight the super secret boss of the game Beast .

https://steamuserimages-a.akamaihd.net/ugc/1753565334716940472/59D870618DD64B8128DE5A687D999C71C480138B/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false
https://steamuserimages-a.akamaihd.net/ugc/1753565334716939490/C779C65C60820214D1B6005114F55D530732958D/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false

[Dataroach]

are they still working on this?

[TrickZTV]

just wait to the 18.11, hype is real

[sevie]

so tl;dr of these comments
- it still works
- it can be laggier than remote play. if one player freezes, so does everyone else. if you're stuttering a lot, use the netdelay command, as you or someone else you're playing with doesn't have a great connection
- it unlocks everything during co-op runs, it does not affect your save file (achievements are disabled)
- certain repentogon modifications can cause desync, as can mods. (quicker room clear especially, as it will desync every room)

[zkbraves]

@That1WeirdKid

try a better cpu? intel pentium

[Adam]

lagg on intel pentium no recomended...

[toromi]

just an FYI for people trying this: beta participation is now over and this no longer works

[dihofortnit2115🔥🔥🔥🔥]

if i do this, does it unlock every item and achievment cuz i heard it works like that

[TrickZTV]

desynced howl time what can i do ? rewind not working

[baby]

Edmund (Creator of Isaac) and the Lead Devs of Isaac, tweeted images showing that Binding of Isaac: Repentance will have a dedicated CO-OP system where you can invite players directly to play with you, track your online streak and much more!!

This is exciting news and hopefully it comes with more stability and less lag!

[ve ¿]

what if i have a problem with "Invalid steamID"