Follow these steps for 2560*1080:

- Open the exe file (BlackMirror.exe) with a hex editor.
- Replace all occurences of the hex values 39 8E E3 3F with 26 B4 17 40 (3 occurences)
- Save the exe, start the game.
- Badaboom! Glorious 21:9!

If you need another resolution, you have to calculate the values yourself:

- Calculate width / height (example: 2560/1080)
- Use a website to convert float to hex (2560/1080 = 2.37037037037 = 0x4017b426)
- Swap the byte order (0x4017b426 = 26 B4 17 40)
- Follow the instructions above with your individual hex values