Point your browser to /gaming/Commandos_BEL_BCD_Ultimate_Fixes.rar. I just wanted you to read what you are getting and understand why. The game will run without but can look ugly so go and find MENU1920.BMP and 1920X1080.WAD from the Internet. Once you have downloaded those two things you might want to also change your ingame menu and ingame UI to support your high resolution.
Most likely you already have it installed but if not just use your search engine skills again. To run the resolution hack program you need Microsoft. The Resolution hack should just have CommandosResolutionHack.exe. The Ultimate fix has a executable named comandos.exe with a size of 3,715,072 bytes and a WARGAME.DIR archive. So just use your preferred search engine for those two mods and you should be fine. I won't give direct links because most likely when you are reading those links would be dead. To get higher resolution in Commandos: Behind Enemy Lines than the original and running the game smoothly you need two mods:
