i downloaded the GOG client and installed the game through the app. when i go to click icon on my desktop it opens the app, then i have to press "play" through the app. but then a window pops up breifley then dissapears saying "run time error" so i cant play.....

Renaming the Galaxy.dll worked in my case. I do get an error message, but the game starts afterwards. Haven't found the time to play it though.
This should relatively easy be fixed?

I have tried this, no luck for me. I have tried so many different stuff posted on the topics now, still not working..

I really hope they find a solution soon. Pretty annoying not to be able to play a game, when you have been waiting for it to be released.

Same problem ... witcher3.exe runs in the background, but the game did not start.

I have tried all "Galaxy" solutions, installed new Nvidia Driver and the .Net 4 Framework , nothing helps :(

A little dump file can you found here: virtuellwerk.de/pub/witcher3.exe.txt

Okay this is no help, but just a random find.
Since I was not able to play W3 I downloaded W2 to spend some time and you know what - it crashed exactly the same as the W3. So chances are there are some solutions already available. Will look more into it, but you can also try searching for W2 solutions.

How do i download the game without installing Galaxy? can anyone tell me, step by step? Cause i can't seem to find it.

From GOG'site, go to your account / library, click TW3 icon and you'll see the instalation files on the left.

No it will not help - I did installation on other machine manually with no result

I read somewhere that nvidia's last driver might cause the crash so i installed older version. Still no change.

I'm having the problem where the game flickers up for a fraction of a second then is gone. I initially preloaded and patched it with galaxy, then when I couldn't open it I found this thread. I unistalled Galaxy which didn't help. I uninstalled the game and redownload and installed from Gog (the 7 separate files) and that didn't change anything. It seems like what everybody else is saying, but I am curious about my graphics card. It's a bit older but I've never not been able to play something before. I have the Geforce GTX 260. Too old?

I'm having the same problem, can't start WT3. I have GTX960

Long story short: If the game does not launch at all, the graphics card (and/or driver version) might be too old.

Here's why: I have 2 systems with 6 GB RAM and Windows 7 64 bit:
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Laptop from 2011 (not for gaming):
GPU: NVIDIA GeForce GT 520M
PROBLEM: Game starts, intro cutscene rolls, Geralt is sleeping by the campfire (rendered with ingame graphics). First loading screen appears, followed by crash to desktop.
FIXED: By updating the graphics card driver to the latest version from 2015-05-18. Now the game runs flawlessly but with 7 FPS (as expected for this system).
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Custom PC from 2009 (once high-end):
GPU: NVIDIA GeForce GTX 275
PROBLEM: Instant crash on launch after milliseconds of black screen.
NOT FIXED. Latest driver version for this card is from 2015-02-20 (v341.44)

Edit: can be fixed by using a GeForce GTX 660 TI
CPU: i5 750
RAM: a quick test showed that even 4 GB could be ok.
MAINBOARD: Asus P7P55D
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In my case the following did NOT work / help:
Installing the game from GOG Galaxy.
Uninstalling Galaxy later and renaming DLLs.
Installing the game manually from the GOG website download.
Installing the game to different hdd partitions (C, D).
Installing Microsoft .NET Framework 4.5.
Installing Microsoft Visual C++ 2013 redistributable (32 and 64 bit).
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Conclusion:
I guess the latest NVIDIA driver update might be critical for the game to run on older cards. My friend has a GTX 660 TI and the game works right out of the box (even without the latest driver). He used the files downloaded manually from the GOG website, just like I did. I'll probably upgrade my PC soon...

Edit: My friend lend me his GTX 660 TI for testing. With that the game starts perfectly on the identical installation. I hope that this information is useful to someone with an old system like mine.
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Side note, for what it's worth:
My crash log files (located next to the witcher3.exe) on both the laptop (before the driver update) and the PC state EXCEPTION_ACCESS_VIOLATION. The callstack always contained (with varying hex number): Scaleform::Render::Matrix2x4<float>::Prepend() + 0x81e00 - <Unknown File>(0)

I am pretty mad right now. I pre loaded the game through GOG down loader, never having touched Galaxy. It failed to work. I then tried using Galaxy. Also didn't work. I tried every fix on this thread. Nothing.

I wiped everything from my computer and tried a clean install through Galaxy. After downloading at a rate of about 0.1-0.2 MBS for about 20 hours, the install reaches about 40%. Next thing I know, there is a big NOT AUTHORIZED stamped across the Galaxy install button. Install completely reset.

At this point I have to leave for the weekend and won't be able to mess with this until Monday. I just really hope GOG gets their act together and fixes this problem.

*EDIT: I should also mention that I am running 16GB RAM and a GTX 970. This issue is not on my end =/

lol at whiners. Give it a day or two, it will be fine you steam whiners.