Just installed Assassin's Creed on my system and when I start it up with Galaxy, or by running any of the EXE files in the game's install directory, or running them in administrator mode, the executable starts briefly, nothing shows and then a second or so later it exits. No warnings or errors are given.

System specs:
AMD Ryzen 5950X
128GB DDR4 3200 CL16 (Gskill Ripjaws V)
AMD Radeon RX 6700 XT (Sapphire Pulse)
3x 2560x1600 displays in extended desktop triplehead configuration, 24bit color, NO HDR
Windows 10 x64

Additional info:
- Not using DPI scaling, just using default.

I searched the GOG forums here, as well as GOG support, PC Gaming Wiki, Steam forums and tried various solutions people suggested to others for similar sounding problems. None of them worked so far, including but not limited to:

- Adding hostnames to the Windows 'hosts' file containing domain names properly configured (not a n00b)
- Blocking the same hosts in the Windows Firewall.
- Rebooting prior to running the game after configuring the solutions above.
- Unplugging the network cable.
- Running all 3 game executables directly in File Explorer both as user and as administrator.
- Running all 3 game executables from the commandline both as user and as administrator with no errors or warnings showing.
- Changing my main display from 2560x1600 (16:10) to 1600x1200(4:3), 1280x720(16:9), 1024x768(4:3)
- Trying all the above resolutions again on the main display but with the other 2 displays disabled.

It seems a lot of people are having problems with this game, and many are upset that it is supposed to be DRM-free but tries to connect to servers that are not online anymore requiring workarounds that GOG should have done something about long ago, which is disappointing and disconcerting.

I bought this game a few years ago on sale just to get it as it was a good price but never tried to play it until now and it doesn't work at all as far as I can tell. The game's store page presently shows the game is officially supported on:

Works on: Windows (7, 8, 10, 11)

So according to GOG it is supposed to, and they expect it to work on Windows 10, so not a "supported OS" issue so to speak.

If anyone has any ideas of what else to try, or some other site I might have missed with my Google search kung-fu, it'd be much appreciated.

Not really sure what other options there are other than to contact GOG support directly to see if they have any magic up their sleeves, and if they can't help get it working try to get a game refund (even though I'm probably way out of the normal window for that, but who knows they sometimes provide exceptional support for such cases I've heard).

UPDATES:
1. I forgot to mention that in my testing above, I also disabled my Antivirus software (Microsoft + Malwarebytes) to make sure they were not interfering with the game, based on someone's recommendation to someone else.

I just reinstalled Assassin's Creed Director's Cut to try it again and got the same results as last time. Did the same attempted workarounds as the first time to no avail. Tried with and without a network cable attached as some people say you need to disconnect networking to get it to work, while other people say that they have the game working even with networking - which makes no sense that both of these situations can work and "disable networking" can be a solution if it works fine with networking for someone else... but hey.

There is an official post directly from an Ubisoft support employee on the Steam forums that say that this game was created before Windows 10 and 11 and that they do not support it on Windows 10 or 11 officially, but they try to help people with it anyway.

If you read enough posts it is clear that some people do get the game working on Windows 10 and 11 without problems, so clearly there is some difference between a system where someone has got the game to work and one where someone has not. Unfortunately the sheer lack of detail that random people out there put into their posts online does not shed any clues as to what the differences can be between a system that it works on and one that doesn't so the overlying situation is one where the vibe is "it works for me therefore you must be doing something wrong n00b". When in reality, there is absolutely some unknown difference between the different people's computer setups but no way to know what it is. Maybe one person is using an Intel processor and another person is AMD Ryzen. Or perhaps some hardware security feature is present on one system and not another. There are a million possible differences, but nobody posts enough info to get even the slightest idea what the problematic issue might be, and everyone posts about things like they are an expert or something when they don't have a clue what the real problem is.

I've went through GOG's troubleshooting guide in the support website and tried every single option and just can't get the game to work at all. I'm left wondering if anyone has ever gotten this game to work with the GOG version of the game and if so, what their exact hardware is - CPU model, RAM, GPU, what version of drivers they have, any particular OS level settings, compatibility settings on the executables, etc.

GOG does claim it runs on Windows 10 and 11, so I presume they have actually got it to work on 10 and 11, I can only wonder what magic hardware setup and Windows configuration they must be using to get it to work though as it clearly doesn't work for everyone.

Surfing google for this is just a minefield of "nobody actually knows why it works for some people and not others, but people pretend to know some magic settings that should work but actually don't and then blame the person having the problem."

Annoying.

Using ProcessLasso and restricting CPU Affinity to the first 8 cores of my 16-core Ryzen managed to get the game executable to actually start up now, display a loading graphic for about 3-4 seconds before crashing. Progress. I've now configured it to only allow core 0, 2, 4, and 6 which would simulate a 4-core processor with no hyperthreading. Same thing, game starts and shows a bit of a video of a loading screen before crashing.

This is the furthest I've got it to go so far though so I'll take that and keep tweaking whatever and see if I can get it going. One take home is that if you have an AMD processor with multiple CCDs such as any 12 or more core Ryzen or Threadripper CPU, definitely try configuring it so the game launches only on one of the CCDs, whether using process lasso, Task Manager or whatever on the Galaxy executable. It appears that whatever Galaxy is set to ends up getting inherited by child processes, so it restricts what cores the game can run on. It's otherwise impossible as the game crashes before you can right click on it to restrict cores.

Additional info:
- Microsoft Defender and Malware bytes are disabled.
- Executable compatibility settings are to disable fullscreen optimizations, and tried to run it in XP, Vista, 7, and 8 compatibility (every option basically), all with the exact same results. XP compat wont run at all and gives an error.

I've tried just limiting it to a single core now as it is an ancient game that would most likely have been made to run on single-core systems back in the day. This eliminates any kind of multi-CPU/multi-core/hyperthreading issue completely. Game crashes same way shortly after launch.

My next thought is dynamic CPU frequency. 2 decades ago the clock frequency of the processor was pretty much static, and a lot of games and other programs had assumptions that this was true in their code. Calibrating timing loops and other similar things based on the CPU clock. Bad idea. Bad Idea Jeans™ Anyhow, Far Cry has that problem during startup which causes it to take 10 minutes to launch the game, but then it works. But if you disable any CPU features that can change the CPU clock speed, Far Cry loads and runs just fine no problem. The nature of this sort of problem could result in any kind of random behaviour including crashes in a game though, there's no way to know without a debugger or other tools.

So... now to try to figure out how to restrict the game to a single core and fix that core's frequency at a specific clock and disable any kind of dynamic control. No idea how to do that, but probably Ryzen Master...

If I get this to work, there should be a GOG Galaxy game achievement for actually getting the game to run. LOL

Ok, tried 2 different ways to limit CPU frequency fluctuations... First one was a hack just for hack sake... I ran 7-zip configured to use 32 threads to max out all CPU cores/threads to warm up the CPU and get the clocks all aligned, then started the game. It made it for 15 seconds before crashing. Best progress so far. LOL

After that I changed Windows power plan settings on a custom profile to set CPU min and max both to 100%. That kind of locked the processor frequency but it still moved around a bit. Game made it to about 10-15s before crashing again, so it does seem like variable CPU frequency does muck with this game.

But at the end of the day, I was unable to get it past the Ubisoft loading screen logo jingle without crashing.

Also, all of this was with the game restricted to 2 cores on the first CCD, with hyperthread logical cores disabled.

Very detailed troubleshooting steps you've taken.
I've also ran into the same issues as i'm using a Ryzen 9 3950x.

Have you tried changing any of the config files in the root director for the game?
I'm unsure where the .ini or .config file maybe that is controlling the default display resolution.

My display is outputting 1440p @165hz and i've been reading that it might cause issues posting the game since it might not be a supported rez for the generation. Something wacking with the physics for anything over 60hz.

Ok so no luck on my end.

I found that the .ini files that were being used are most likely generated once the game is launched and runs an initial config in the background to establish the settings are not there to be edited.

I tried manually creating both .ini files in hopes that it was this the .exe were hanging on.

https://tweakguides.pcgamingwiki.com/AC_9.html

Quite a coincidence, that I also had that issue in February (24th) and now in autumn also tried it again. It came to my mind to use the fix for Witcher 2, which I started one week ago and it worked for this game too.

The game refuses to start with 32 cores. It starts with 31 or 8.
AMD Ryzen 9 3950x

It starts and lasts between 3 and 15 seconds here then crashes to desktop no matter how many cores are configured. The game has some kind of race condition which varies from system to system the extent that it's going to be affected it seems, as the failures do not seem completely consistent even with the same processor in different systems.

I get more or less the same results with 16 cores, 15, 14, 13, 12, 8, 6, 4, 2, 1 which are what I tested so far, as well as variations on some of them splitting between the 2 CCDs. The only thing that I've found gets the game to run longer before it crashes is forcing the CPU to get 100% usage on all 16 cores/32 threads by running 7-zip to compress a huge amount of video files, which in turn causes all cores to run at roughly 4.4GHz fairly consistently. This leads me to believe the game has a timing race condition between threads when individual CPU cores frequencies fluctuate.

Hard to say for sure, but I still haven't found a way to get this game to run on my 5950X without crashing within 15 seconds or so.

Could it be, that you simply »unlocked« another problem with the fix ? Originally it didn't start at all.

I have the same cpu and same problem, os win11. Found a solution so far, go to properties, compatibility windows 98 and disconnect from the internet. It seems to work, I don't care for this solution though since I play most of my games through moonlight on my phone. No internet, no moonlight. If anyone has an answer to the internet issue with the game please shoot a post.

Had the same problem with my Ryzen 9 7950x3d and Win 11. I remembered having an (on first look) similar issue with Witcher 2 and remebered this solution:
https://www.gog.com/forum/the_witcher_2/solution_witcher_2_doesnt_start_on_windows_10_frozen_splash_screen

I tried this Witcher 2 Fix with Assassin's Creed Director's Cut and it seems to work just fine. I played through the tutorial without any problem.

Create a new file in the Main Folder of your game and name it as you like. I named it "CPU Core Fix.bat". The ".bat"-ending is important though.

Then edit this file with an editor like notepad++

You need to add the following code:

D:
cd "D:\Games\Assassins Creed"
start /NODE 0 /AFFINITY 0xFF AssassinsCreed_Dx10.exe

Change D: at the beginning of the code to the drive where your Game is installed. You'll probably have to change the path between the brackets to your game installation path as well.

Save the file. Use it to launch the game.

If you are using gog galaxy you can edit the games configuration and make the .bat-file the standard file shortcut to launch the game this way permanently (at least till your next reinstallation).

Edit 14.01.23: Played through several sequences now and the game is running stable. No crashes so far.

TLDR this forum. But did you try game mode in the Ryzen Master? It cuts your cores to 8. Worked for me. The option may also be called 'Legacy Gaming'.