Desync Workaround using Dropbox and mklink

[PsychoAngelic]

I also posted this in the Steam forums, hopefully this works for some of you.

Greetings!

While emailing saved games is OK, I found this troublesome and hit-or-miss as the desync can occur before the save and then you're screwed and have to start over. So, I decided to test using dropbox as a workaround with a friend. So far this has worked with no issues and is completely automated so there is no need to email or upload the save all the time.

The system I came up with is as follows, which works with a brand new game after turn 1 when a fresh save is made and not after:

Host Instructions:

1) Both parties will need a Dropbox account

2) Install Dropbox and create a save game folder to be shared.

3) Navigate to your saved game folder (normally found in "C:\users\<yourname>\appdata\roaming\the creative assembly\shogun2\save_games_multiplayer"

4) In the folder from step 3, move the file named "autosave.save_multiplayer" to your newly created Dropbox shared folder. In my case it was "C:\Dropbox\Shogun2"

5) Delete the file "autosave.save_multiplayer" from the folder identified in step 3.

6) Now using the command prompt you will need to set up a symbolic link in windows to allow the game to save correctly. The syntax for a symlink in this case is as follows, though you will need to change directory/username info specific to your system:

mklink "c:\users\<yourname>\appdata\roaming\the creative assembly\shogun2\save_games_multiplayer\autosave.s ave_multiplayer" "c:\dropbox\shogun2\autosave.save_multiplayer"

Effectively, this creates a shortcut to the file allowing you to change your autosave location.

7) The host will need to share the dropbox folder with whoever they need to.
8) Everything should be good to go.

Connecting Player Instructions:

The connecting player will need to do all the above steps except in step 4 instead of moving their autosave, they will need to take the autosave from the host's dropbox folder and place it in their dropbox folder which creates the initial saved game synchronization.


Other Notes:

-It is strongly recommended you do not have any other save game data in your multi-player save folders


Let me know if this works for anyone. This has been working for my friend and me for about 50 turns so far with multiple loads (not continuous play).

Update: Completed a game with no problems using this and am now playing a RotS game with no problems so far.
Edit1: Changed formatting to remove ambiguity on connecting player's instructions

[sgtgumbo]

Wow....

Well done sir.. I will give this a try =)

[HeroicSpur]

How do the multiple dropbox accounts work? I thought you could only share a dropbox folder when you used the same account. Can 2 different accounts share 1 folder?

[HeroicSpur]

Ah sorry, I just checked dropbox site, found the answer. This looks the kind of thing that hits desync at their source (the moronic system which allows two computers to produce divergent outcomes, rather than forcing the host to determine all outcomes). Lets hope this works, and thank you PsychoAngelic.

[PsychoAngelic]

This looks the kind of thing that hits desync at their source (the moronic system which allows two computers to produce divergent outcomes, rather than forcing the host to determine all outcomes).

Correct. The autosave feature saves as an unique file on each person's computer. When a new game is started, the saves are likely to not be identical and the CPU calculates things differently during the AI moves (I'm assuming). This method bypasses the autsaving on the connecting person's end, forcing use of the host's autosave upon resuming the game after a break.

I'll update again when I've tested it more.

[BOTA:99]

How is this different than the host doing a file transfer over skype? It does the same thing forcing both computers to use duplicate saves?

[HeroicSpur]

I'm not sure how Skype works but dropbox works automatically. Any files in the dropbox folder are automatically synched. Therefore, if I have this right, the autosave is moved to the dropbox folder, which is shared. Both machines refer their Shogun 2 autosave to that dropbox folder. Therefore everytime an autosave is made, it is automatically synched and this means the connecting player always uses the hosts save file.

My only concern is this, even if the game is continually using the same save file, does that stop the game becoming divergent during the actual game? Surely the game doesn't load the autosave every turn. So could the game still desync? I suppose it depends on how exactly the autosave file is used and what data it contains.

On a further note, what impact do you think this has for non-autosave files? Do you think it's advisable to only use the autosave?

[PsychoAngelic]

My only concern is this, even if the game is continually using the same save file, does that stop the game becoming divergent during the actual game? Surely the game doesn't load the autosave every turn. So could the game still desync?

Possible, but unlikely. In my experience, desyncs would generally happen after resuming the game, not continuous play. I have noticed that the game auto saves two separate files for each save, one on the host the the other on the connecting player after each individual player's turn and both of those saves are the ones used to resume the game (which is a poorly designed system CA) and this is why emailing saved games sometimes works.

So, why doesn't emailing always work?

I do however think that previous save information is carried over into newly created saves (i.e. autosave data being used to create quick/manual save data). If my assumption is correct and based on my before mentioned observation, this suggests that due to the different autosave files for each player, the desync happens when either the game is resumed from a non synced autosave or a quick/manual save is used that utilized desynced autosaved data.

On a further note, what impact do you think this has for non-autosave files? Do you think it's advisable to only use the autosave?

For the reasons I describe, I would suggest only using the auto saves under this method until CA actually fixes the issue. Not only that, quick and manual saved have a unique file name in the Appdata folder, so using dropbox and symbolic links would be very problematic. The autosave file is the only file in there that is constant. If you insist on using the other saves, you should just stick to email/skype/etc.

[Remair]

This sounds really promising Psycho. I'm a bit sceptical (too many years wanting real TW multiplayer and being disappointed to get my hopes up) but will keep an eye on this thread, let me know if you manage to finish a full campaign. If this does indeed fix it then frankly CA should pay you for doing what they've been unable to do for a year

[insolentfool]

A friend and I played like 8 hours straight in campaign without loading. on legendary so we only have the one save. about 40 turns in the host CTD. we loaded the game and 2 turns later had a battle on only my screen. Sure the desync was after the load, but i believe the CTD was caused by desyncing.