*2021 edit: The guide still works. Tested with Windows 10 and 2560 x 1440 resolution

To get higher resolution in Commandos: Behind Enemy Lines than the original and running the game smoothly you need two mods:

• Commandos Ultimate Fix by Doc Garga
  
• Commandos Resolution Hack by stevenh

I won't give direct links because most likely when you are reading those links would be dead. So just use your preferred search engine for those two mods and you should be fine. The Ultimate fix has a executable named comandos.exe with a size of 3,715,072 bytes and a WARGAME.DIR archive. The Resolution hack should just have CommandosResolutionHack.exe. To run the resolution hack program you need Microsoft .NET framework 4. Most likely you already have it installed but if not just use your search engine skills again.

Once you have downloaded those two things you might want to also change your ingame menu and ingame UI to support your high resolution. The game will run without but can look ugly so go and find MENU1920.BMP and 1920X1080.WAD from the Internet. I used ones made by Ferdinand Zeppelin.

ps. I lied. Here's a direct link for all of those. I just wanted you to read what you are getting and understand why. Point your browser to kruulos.org/gaming/Commandos_BEL_BCD_Ultimate_Fixes.rar . If the link goes dead, sorry about that. At least you know what to search for.

So let's set the game up then.

1. Go to your game folder "...\steamapps\common\Commandos Behind Enemy Lines" and back up your current game executable and your current WARGAME.DIR in case something goes wrong
   
2. Copy the fixed exe over the original and copy the new WARGAME.DIR over the original
   
3. Rename the fixed exe from comandos.exe to something else like commandos.exe or shooteyhideygame.exe.
   
4. Run "CommandosResolutionHack.exe" and select your renamed & fixed exe. This will unpack the WARGAME.DIR. BEFORE you press Apply and Run do the below tasks!
   
5. Copy MENU1920.BMP to "DATOS\recursos\bmps\SYSTEM\MISC"
   
6. Copy 1920x1080.WAD to "DATOS\recursos\bmps\SYSTEM\GLOBAL"
   
7. Edit "OUTPUT\Comando.cfg" and insert these lines at the end of it:
   
   .SIZE [ .INITSIZE 3 ]
   .PROFILE [ .USER 0 ]
   .DEVELOP 1
   
   
8. Now in the CommandosResolutionHack select your preferred resolution on the dropdown. You can try multiple different ones until you find one that's suitable for you. In 2021 I tried it with 2560x1440 and it works.. but isn't very nice experience as there will be weird graphic artifacts as the game just doesn't know what to draw in the empty places on the first scenarios.
   
9. Before selecting the resolution and pressing "Apply and Run" read the last notes first

If your game is not running in the right resolution, go to game video options and try to change the resolution to the highest there. You should only need to apply the resolution hack once. After that you should be able to run the game without the launcher (ie. directly from Steam).. If Steam is trying to repair your installation when you launch it via the Library, it will remove all of the work you did above. In that case redo everything and keep launching the game via your renamed exe manually.

Now your game should look like this

• Weird graphic glitch on the right side of screen
  
• Some maps are below 1920p width. There are at least two and most notably the first mission. Just use + and - keys to zoom in and out.

• I don't have DIRECTX 5??
  
• You didn't either launch from the resolution hack exe or Steam 'repaired' your work and renamed it back. Do it all again and read the guide step by step.

• I want to skip the intro
  
• just rename the "VIDEO\h_intro.avi" to something else

• Game runs on hyperspeed
  
• You are not running the Ultimate Fix executable then. Make sure you apply the resolution hack to right exe. The resolution hack should say it is 'GOG.com Ammo Pack version'/'Commandos Ultimate Fix'

• I can't save or load
  
• Make sure you have the .DEVELOP 1 in your Comando.cfg

• Game randomly freezes
  
• I had this when I was running on compatibility mode for XP & 98. It has something to do with music and sound. I didn't get any freezes when I dropped the compatibility mode.

• Game randomly loses music & voices
  
• Related to the previous one. Just save and restart the game. Next time you reload it should be fine. Happened a lot with the mission objectives. Just restart the mission and you will hear them.

• I want to use different resolution than 1920x1080
  
• I advice against bigger resolution as you will run into problems with game map widths and zooming. If you want smaller one just pick different resolution from the resolution hack launcher and go find proper BMP/WAD resources so your ingame UI and menu will look good.

• This game is hard
  
• Yeah. Learn the hotkeys and get better at it.