This workaround may help get the game running on some systems (we haven't yet determined what kind of system may be affected).
Try launching the game, ideally by right-clicking its shortcut and selecting "Run as Administrator".
Press Ctrl-Alt-Del and open the Task Manager.
Right-click game.exe (or sentinels.exe, for the expansion) and click "End process". Confirm if necessary.
Do not close the Rundll32 process.
Launch the game again. It should now work, with the Rundll32 process already running. You may need to repeat these steps every time you launch the game.