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Add ability to run multiple game instances for testing purposes
Closed, ResolvedPublic


Currently Steam prevents me from running multiple instances of ARMA 3:
Failed to start game (app already running).

This is a problem for me as a scripter. When working on multiplayer scripts I need to be able to test in a multiplayer environment. The optimal approach is to run 2 instances of the game at once, one to act as the server and the other as the client. Steam prevents me from doing that.


Legacy ID
Steps To Reproduce
  1. Start ARMA 3
  2. Attempt to start ARMA 3 again

Event Timeline

Deadfast edited Steps To Reproduce. (Show Details)Mar 9 2013, 3:14 PM
Deadfast edited Additional Information. (Show Details)
Deadfast set Category to Other.
Deadfast set Reproducibility to Always.
Deadfast set Severity to Feature.
Deadfast set Resolution to Fixed.
Deadfast set Legacy ID to 1846009310.May 7 2016, 11:58 AM

I was about to post this exact issue, but found yours.
This is not just a feature request, this is a MAJOR issue.

Having to pull in friends every 2 minute to see if your change works is not fun. And you lose all your friends.

In ARMA 2 the game would tell you you were a pirate if you started 2 instances on the same machine, but at least you could test.

We need to be able to do this! Also without being called a pirate.

Agreed. I'm Deadfast's friend, but not for much longer if this request isn't implemented!

I am looking for the same ... Has anyone found a workaround?

Since it's a steam only game, the likliness that you'll be able to run two instances are not in the devs hands, but rather in steams. I do not believe that they will go in and change the code for steam just so we can test it.

Why don't you try and be social and try and work with other people? There's a community of testers out there. Post in the forums to see if someone wants to get on skype or TS with you to help you test things out.

Imagine if developers had to release their app every 2 minute and wait for testers every time they needed to test something.

That would slow down development many thousand times.

I don't think you quite realize how testing works xzen. There is a difference between asking someone to come and help you test something for 15 minutes and asking him to sit with you on Teamspeak/Skype the whole day just so you can test something every now and then.

How would you determine which of the instances is the original to distinguish it from possible illegal copies - seems like the inability to do so was the real reasoning behind auto-labeling players as pirates. Lifting this restriction would lend the game to more hacks, exploits and actual pirates. No, thank you.

epoch71, what do you mean? Buy your own ARMA 3 copy, if you haven't already.


I really don't think you realise that there's other people out there that want to test out multiplayer scripts too. Why don't you load it up on another computer, and run one of your clients with steam offline?

I can only be logged into Steam in one place at a time. Unless I connect multiple monitors and input devices to my computer no one but me will be able to play the game, even if I start multiple instances of it.

epoch is the poor sod I have to annoy every 5 minutes when I need to test something in MP.


I'm going to go on a limb here and guess you haven't actually made any MP scripts yourself. The issue isn't the lack of people willing to test a script, the issue is the lack of people willing to test the same exact script every 5 minutes to provide the necessary feedback during *development* of the script. And even if there were, there are logistical issues involved as well. I have to redistribute the script every time I make any changes to everyone. I currently do use a second computer with the game running in offline and everything synching via Dropbox but even so it's a major hassle that I could live without.

You'd be correct in saying that I have no experience with making my own scripts. If you would like I can help you out for the next couple hours, as I am doing nothing but scrolling through tickets and would like to jump into this wonderful world of scripting.

@Tourorist: Which of the instances is the original? They're both original. It's extremely easy to check whether all players connected to a server are connecting from the same IP.

I did a bit of searching and it's possible to run multiple instances at once after all:

  1. go to your arma 3 directory(steam/steamapps/common/arma3)
  2. then make a new txt file called "steam_appid"
  3. type "107410" into the file

That's it you can run multiple games at once. I was able to host and join my own local network game, and the game behaved just as you'd expect. There were no problems of any sort. That said you are running x2 copies at once, so system usage will double. Maybe now we'll finally see 100% CPU usage hehe

Update: I was also able to run a server instance with 2 client instances simultaneously on the same machine, so we finally have a way to test multiplayer scripting.

@naizarak: Yay! Thank you! It freaking works!
And you don't get called a pirate in this one :D

That's the same workaround used for cracked games.. so basically you are cracking ArmA3 (even if you bought it, it's still illegal due to steam policies)

I would imagine cracking a Steam game involves a bit more than creating a text file.

Yes it does because you have to "remove" the run via steam from game's exe.
But the fake ID (which is basically a free to play game ID) is one of the steps and it's still against steam policies.


Please point me to the part of the EULA that prohibits me from creating text files.

Hanz added a subscriber: Hanz.May 7 2016, 11:58 AM
Hanz added a comment.May 9 2013, 2:27 PM

This suggestion was processed by our team and will be looked into. We thank you for your feedback.

While the game is in alpha, and beta for that matter, being able to run more than one instance of the game for testing purposes locally is very important for feedback.

Issues such as #0000716 especially in MP are very hard to reproduce consistently, but could possibly be understood when tested under controlled conditions.

Beyond that, it would also be nice to be able to run a limited LAN capability when Arma3 goes gold.

Addon and script development that have a strong network component are almost impossible to refine where differing machine hardware, random network problems, and finding willing test partners simply exacerbate the issue.

Even with two activation keys for Arma3 it is impossible to run two instances. Steam prevents two activations under the same user, and only one user can be logged in at a time. For the record, this is not mentioned in the EULA either, and cries of piracy are rather moot.


It is possible to run concurrent instances after applying the fix mentioned in ~0008202. This does not defeat Steam, nor does it allow multiple installations using the same activation key for LAN play for example. Attempting to join an online server may trigger duplicated key alerts, or even result in your Steam account being revoked.

The old method of adding -window -nopause to a shortcut created from arma3.exe will enable full testing of MP missions and addons between two or more windowed clients depending on the host machines hardware of course. Simply run as many copies as required from the same shortcut.

Terox added a subscriber: Terox.May 7 2016, 11:58 AM
Terox added a comment.Jun 11 2013, 5:25 PM

this is no longer an issue

X39 added a subscriber: X39.May 7 2016, 11:58 AM
X39 added a comment.Jun 22 2014, 10:37 PM

am im the only one who is not able to run multiple instances with this workaround anymore?

I think this should be marked as solved.

Steam now opens the launcher instead, which can be used to launch multiple instances (only with the same mods selected though). You can also launch the game directly from the executable multiple times without any interference from steam as far as I know.

The only problem I have is launching the game from steam while my dedicated server is running. Going to make a separate report about that one though since this is so old and not 100% relevant.

As soon as I go to reproduce the server issue to be sure while making the report I find it's been fixed. :P

You can also make simple shortcuts and start multiple instances this way.