Disable auto resolution in vorpX and select your custom resolution in the game’s settings.
vorpX can handle any resolution or aspect ratio you make and run from a game’s settings menu. The question is whether the game itself supports them or not. Some brief trial and error can quickly determine this.
An easy way to find resolutions is use a calculator to multiply the base aspect ratio. I like to step in tenths to keep it simple (1.1, 1.2, 1.3). A 4:3 example: 1600×1200 x 2.1 “1600 x 2.1 = 3360, 1200 x 2.1 = 2520” = 3360×2520. Then see if your monitor passes the test.
My monitor seems to like odd numbers better and can go higher than some even resolutions that fail.