Sometimes there is an issue with the video game "urban error is due to the graphics card or the chipsets. Since urban error can also take place. You can solve this problem by updating the graphics card driver or editing the file resolution - see below.
When I launch Urban Terror, the console opens on a blue background indicating this message:
CLW_StartOpenGL() - could not load OpenGL subsystem
This error is directly related to your graphics card or chipset. The latter does not support the "compression engine for 3D OpenGL". Urban Terror runs with this engine. This error occurs mostly on older PCs with only average performance.
It also occurs upon the modification of the resolution in the game (unsupported by the Graphics card).
Update the graphics card driver
This is the easiest solution, (note that it is not safe on some PCs). So follow these instructions:
Create a restore point: Start, Accessories, System Tools, System Restore.
Select "Create a restore point", give it a name and let the tool work.