This is a modification of the original Quake2.exe (smaller than Steam's or GOG's) from
You can change the resolution using the gl_mode variable in the console (for example press the ~ key then enter say gl_mode 5), or via the menu. Windowed mode will only render correctly at high res if you check the 'overide high DPI display scaling' checkbox (right click Quake2.exe, select compatability to find it, thanks Consumerist!) Press alt-enter to toggle windowed/fullscreen.
