It seems like the game requires DX11 and Proton tries to use Vulkan support to run it, which the card doesn't support, as it uses the radeon driver instead of amdgpu. The game shows "Failed to initialize graphics. Make sure you have DirectX 11 installed, have up to date drivers for your graphics card and have not disabled 3D acceleration in display settings. InitializeEngineGraphics failed". The game runs with WineD3D, but the video is so garbled, that it's unplayable. On Windows it runs fine, as the card supports DX11.