i had this exact problem but i found someone on the steam forums who helped me fix it.
this is his post on how to fix it. i have a gt 420m but it happened to me too. The problem is that Worms Ultimate Mayhem by default will often use the wrong Video driver. It was using the integrated graphics drivers instead of the high-performance NVIDIA drivers. if all you have is an integrated graphics card then there's a strong chance u just can't run the game and this won't help you.
Just change the program setting for Worms Ultimate mayhem to use the high-performance NVIDIA drivers in the NVIDIA control panel.
Step by step: Control Panel -> Hardware and sound -> NVIDIA Control Panel -> 3D settings -> Manage 3D settings -> Program Settings
Click Add
The default location for the Worms Ultimate Mayhem executable is:
C:\Program Files (x86)\Steam\steamapps\common\wormsxhd\WormsMayhem
for 64bit Windows systems.
C:\Program Files\Steam\steamapps\common\wormsxhd\WormsMayhem
for 32bit Windows systems.
Under the "Select preferred graphics processor for this program:"
choose "High-Performance NVIDIA processor" from the drop down list.
Apply the changes and Worms Ultimate Mayhem should now run.
If this did not work for you:
-You could test if you have applied this method correctly by temporarily changing the global setting to High-performance NVIDIA processor. If this fixes the problem and my method did not then there was a mistake in the application of my method, if it does not fix the problem, other possibilities would have to be explored.(Do not leave your global setting as High-performance NVIDIA processor, this will eat up a lot of performance and battery life for applications that don't need it)
-If you used the right click method as the next post indicates, contrary to what the post says make sure you change the default graphics processor, as running WormsMayhem.exe with High Performance processor directly from the right click menu starts the launcher first and then you can start the game from the launcher, however it launches the game with the default setting, nullifying the use of running it with the high end graphics processor, also you will only see the option to "Run with graphics processor" if you right click the WormsMayhem.exe in its steam directory not the desktop shortcut.
-Make sure you are applying the change to WormsMayhem.exe and not Launcher.exe