If your game flickers after launching a level, you should try forcing Vertical Synchronization (VSync) to OFF. We have encountered this problem on nVidia GeForce 8 series graphics cards.
To turn off VSync you must open your nVidia Control Panel by right-clicking your desktop or the nVidia icon in your system tray and selecting NVIDIA Control Panel.
Once inside the Control Panel you should create a profile for the game. To do so select the Program Settings tab (located in the 3D Settings->Manage 3D settings group) and click Add. Find your Evolva folder in the newly opened window (C:Program FilesGOG.comEvolva by default) and double click the evolva.exe file.
Once you have created the profile, scroll to the end of the list of options and find "Vertical sync". Select "Force off" in the option's drop down menu and press the Apply button.
You can now close the Control Panel and the in-game screen should stop flickering.