I change a new resolution, but the game only open in 800x600

The game's menus has the fixed resolution of 800 x 600, however during the actual play the game will change to the desired resolution you set in the configuration.

I can confirm the resolution of the main menu is hardcoded at 800x600. This gave me some trouble, but thanks to the support I was able to get an acceptable workaround. But I digress. The game itself is rendered at the selected resolution once the match is loaded.