Downgrade Enemy Unknown to Patch 4 (356266) R&D

[Bertilsson]

The other day I did some thinking and came up with the following idea:

 

What if we were to create a mod for downgrading Enemy Unknown Patch 5 to Patch 4 instead of upgrading all mods to Patch 5?

 

After some experiments together with bokauk we have been able to conclude that: XComGame.exe Patch 5 (file version 1.0.0.55175) can be converted to Patch 4 (file version 1.0.0.28586) on different computers (with different steam accounts) using a single diff file created using BSDiff.exe (thank you DubiousIntent for discovering that tool), and will still start without any problems.

 

So what I want help with from the rest of the forum is to figure out what more needs to be done in order to create a downgrade patch for Enemy Unknown in order to be fully compatible with all existing mods and if there are any differences if user has any or none of the DLC's.

 

And probably A LOT of testing to make sure everything works as expected once the mod is complete :smile:

 

So exactly what has changed between patch 4 and patch 5?

 

What must be downgraded for the game to work and to be fully compatible with all existing mods? (XComGame.exe, XComStrategyGame.upk, XComGame.upk, XComShell.upk and Command1.upk, something else?)

 

Anything else to consider? such as movie files deleted/moved?

[wghost81]

What about EW compatibility? EW does use some of EU resources and this was a compatibility patch (not only, but mostly, as 2K say). Edited November 26, 2013 by wghost81

[Bertilsson]

What about EW compatibility? EW does use some of EU resources and this was a compatibility patch (not only, but mostly, as 2K say).

That is part of what needs to be figured out. In my experiments I have used a .rar backup of my Enemy Unknown folder to overwrite all duplicate files in the old XComFolder (not touching XEW folder) and from what I can tell EW doesn't seem to mind... But yes there is very likely shared files which needs to be copied and or modified in order to downgrade to EU Patch 4.

[Bertilsson]

I have now done a little file comparison between EU patch 4 backup and EU Patch 5 (excluding the XEW folder) and this is the result:

3835 files identical

122 files different

122 files only existing in Patch 4 folder (missing in patch 5)

3 files only existing in Patch 5 folder (missing in patch 4)

The 3835 + 3 files which are identical or only existing in Patch 5 are of no concern as they can simply be left alone.

The 122 files which are different (including XComGame.exe) can be downgraded from patch 5 to patch 4 via diff files created with BSDiff.exe

The 122 files which are missing is a bit more complicated to deal with.

A big portion of the files are movie files which seems to have been replaced with 1080p versions under a different name (~adding 1080p to the name and placing them inside shared folder for EU and EW inside XEW?).

The proper way to deal with those files would probably be to copy them back to original location, rename them and downgrade them to patch 4 "low-res" versions. But I am not very amused by the prospect of figuring out the exact details as to which files became what files (with or without DLC's). Especially not if the entire purpose of the exercise is to degrade them.

So what to do with the 122 missing files which will most likely be required by XComGame.exe Patch 4 version?

I can't just take my patch 4 versions of them and put them into a zip archive and distribute them as is since that would be very questionable from a copyright perspective.

I don't want to spend a month attempting to reverse engineer what happened to them.

However I can use BSDiff to create diff files based on them in combination with an arbitrary selected file which is already part of the game package.

The result of that action would technically be that the resulting diff file is a blue print of how to convert the arbitrary selected file into the missing file.

Another way to look at the resulting file would be that it is an encrypted version of original where the arbitrary file is the encryption key and BSPatch provides the decryption algorithm.

Regardless of chosen interpretation the end result is that the files cannot in any way be used to pirate the game since they are by definition just a worthless pile of zero's and one's to anyone who doesn't already have the game available as base for reconstructing the files.

Next step is to look into the practical side of how to create the needed diff files and an installer for them.

Most likely I will create a vbscript for that task during the weekend unless someone comes up with a better idea... Which seems highly unlikely based on the current activity in this thread :smile:

BTW all above is completely limited to the steam common folder... But from initial testing I did not find any issues running Patch 4 with Patch 5 version of my documents\My Games\stuff, so hopefully my documents can be completely ignored and otherwise it would likely just be more of the same.

[Drakous79]

I've decided to delete all movies from backups (around 30 GB free space), after EW compatibility patch came out. The reason for it was a decision to move on, because EW is good expansion and in my book :smile: it completed the game. There is some stuff that needs fine tuning, but the game is quite enjoyable atm. Would be nice to know numbers, like how many people upgraded and how many didn't.

 

Those missing files might be 720p video files. Found two links regarding this matter:

• Quick note about XCOM: Enemy Unknown's video assets in the PC port
• How to force XCOM to use 1080p cinematics

I feel like downgrading to EU patch 4 is kind of crazy. Basically you're doing mod author's work and that is very kind of you. I only wish modding the game could be easier in terms of adding and keeping new stuff instead of hex-rewriting old.

Edited November 30, 2013 by Drakous79

[Bertilsson]

I feel like downgrading to EU patch 4 is kind of crazy. Basically you're doing mod author's work and that is very kind of you. I only wish modding the game could be easier in terms of adding and keeping new stuff instead of hex-rewriting old.

I couldn't agree more. Downgrading from EW to any version of EU would be insane.

 

However I have no intention of downgrading EW, only EU to P4 in order to make it compatible with existing mods.

 

On the topic of missing files it does indeed look like the 720p movies explains at least 93 of the ~120 missing files

 

I have already started tinkering with a script that will basically do everything automatically in order for simple remake if/when patch 6+ arrives.

 

Right now I'm trying to figure out what is different between EU with and without slingshot and enemy unknown. Does anyone have any insights on that topic?

[Drakous79]

Yeah, I meant downgrading EU P5 to EU P4. Depends on EU getting any updates in the future. If not, mods can be updated and stay like that for ever.

 

Why does EW need EU? Slingshot seems to be fully integrated into EW. Compared files between EW and DLC_Day60 CookedPCConsole and few files had different names or size. Failed to find only three files: CIN_DLC1_DropshipIntros.upk, DLC_Day060_SF.upk and NarrativeMomentsDLC60_SF.upk.

 

There's something strange about XCOMLauncher.exe. So far I was unable to run EW without it, plus if I rename the file, EU starts.

 

Difference between EU with or without Slingshot may be XComGame\DLC\PCConsole\DLC_Day060 folder. Checked file sizes between EU 346964 and 346964 with Slingshot and they were the same except DLC_Day060 folder. Also there may be some INT files updated in My Documents (XComGame.int, XComStrategyGame.int and XComUIShell.int), as I remember BlackAlpha asking for those files in the past.

[Bertilsson]

Good news for all troglodytes longing to play & mod Enemy Unknown Patch 4 again.

 

I have now downgraded my installation of Enemy Unknown Patch 6 to Patch 4 using only a script, bspatch.exe and 4063 diff files with a total size of 2.92 GB :)

 

From initial testing using toolboks 1.52 and some random mod options, including increased squad size, everything seems to work 100%

 

Next step is to find volunteers willing to beta test before uploading as a mod.

 

If interested, please send PM and let me know which DLC's you have, as I would especially like to know if it works with and without the DLC's.

[Amineri]

:blink: Gee ... only 2.92 GB of diff data? I'm glad you specified the extra 0.02 GB so that people didn't get the wrong expectations :)

[Bertilsson]

The 0.02 GB is the total size of the diff files not dealing with missing movies, so it is really the most important part of the mod :)