I too cannot launch Rebellion. Rebellion worked for me for years but I am having the same problem noted by Caswallon. I have looked through all the "recent" threads online to attempt to fix this problem.
I followed many different varieties to get the game going to include: 2 full re-installs with restart of PC. I have verified the integrity of the game files each time, both from within Steam properties and through the Stardock launch window. The Stardock launch window states there is a file missing then I watch as Steam downloads something, but once again the file comes up missing.
As the administrator, I edited the settings file. I tried the default settings. I tried with Windows TRUE. I tried lowering the screen resolution, as well.
All in all I have been troubleshooting this problem for the last two hours and have ended up here frustrated. I have a large assortment of "minidump" files that I have no idea who I should send them too.
Here is the first error that repeatedly comes up every time when trying to launch Rebellion through Steam on my Windows 10 high end PC.
Assert @ D:\SinsRebellion\main\CodeSource\Engine/File/FileSystem.cpp(408)