Every time I try to launch the game it start in window mode, show some logos then the Endless Legend logo and BOOM close himself and nothing more.
I tried everything I can : re-install, check all files with steam, run the game as admin, run with the 32bit mode, with Windows 7 and 8 compatibility, make sure that folders are not in "read only", launch the game with steam closed, use “-useembedded” and “-useshellexecute”.

I tryed to re-install .NET but it refuse to since I already have a more recent version than 4.5.1 on my PC...

I tryed the Nvidia thingy but since all instructions I find are in english and my PC is in french, everything is named differently so what I tryed seems to be completly uneficient.

So I'm here, with a game that worked perfectly for several months, trying to understand why nothing is working anymore without a single clue ...

Specs : 

 - OS : Microsoft Windows 10 (build 16299), 64-bit  

 - Processor : Intel(R) Core(TM) i7-4720HQ CPU @ 2.60GHz

 - Video Card : NVIDIA GeForce GTX 965M

Dunno the game version since I can't reach main menu but since I just re-downloaded several times today it should be the last one.

Files :

EndlessBug.zip

Thank god. For me the application is working again.

in short: uninstall the application and remove the folders "Program Files (x86)\Steam\steamapps\common\Endless Legend" and "Users\[username]\OneDrive\Documenten\Endless Legend" then reinstall and it should work.

more details:

When i last tried a new install i had a look at the folder which remained. In there i found the output_log.txt file (in the "EndlessLegend_Data" folder in the endless legend folder).

This file seems to contain a log of the last failed start up of endles legend. I find the following error there:

An exception has been raised while initializing the application:
System.UnauthorizedAccessException: Access to the path "C:\Users|[username]\OneDrive\Documenten\Endless Legend\Temporary Files\f2234a2f-d590-4357-a96a-f9a6b183b961" is denied.
  at System.IO.Directory.Delete (System.String path) [0x00000] in <filename unknown>:0
  at System.IO.Directory.RecursiveDelete (System.String path) [0x00000] in <filename unknown>:0
  at System.IO.Directory.Delete (System.String path, Boolean recursive) [0x00000] in <filename unknown>:0
  at System.IO.DirectoryInfo.Delete (Boolean recursive) [0x00000] in <filename unknown>:0
  at (wrapper remoting-invoke-with-check) System.IO.DirectoryInfo:Delete (bool)
  at Application+<OnApplicationIgnitionComplete>c__IteratorE6.MoveNext () [0x00000] in <filename unknown>:0 

(please note the folder seemd to be empty to me)

I then deleted also the folders
Program Files (x86)\Steam\steamapps\common\Endless Legend and
Users\[username]\OneDrive\Documenten\Endless Legend

and then did a new install. At the moment it seems to work fine (i as able to start the game) but it now starts in windowed version. However that should be fixable in the options.

Note, the one drive also seems to contain your save files.  so maybe better to copy that folder to a different location?

OK, I got the problem ! It was Bitdefender 2018 "Ransomware protection" that was preventing any access on "\Document" folder. So I just had to desable this useless fonction, make sure that Endless Legend Application have access granted to "\Document" and the game is starting correctly now.

Right now I have the "argument cannot be null. Parameter name: archive" problem while trying to generate a map...

 But problem solve by using "useembedded" in launch option in steam.