Please refer to Ranger Elite for information on how to fix the DLC.
Ranger Mode Hardcore takes your Metro experience to a whole other level. With Ranger Mode Hardcore, everything on your HUD is disabled, so you won't be able to see the action button prompted, or any of the in-game menus to choose bullets, weapons or charge your headlight. Everything still works, but its much more limited. Weapons, ammo and filters are also limited. You will want to scour as many supplies as possible when playing the game so you do not run out of anything. Enemies will also deal more damage, but your guns also deal more damage.
Here are some tips to help you on your way through Ranger Mode Hardcore.
Watch your watch. The little wristwatch is the single most helpful tool in the entire game in Hardcore. Both the timer and the blue light will help tremendously. If the blue light is on, this means that you can be seen by any enemy within eyeshot. If you have your gasmask on, and the timer goes below :59, then that means you have less than one minute left on your current filter. Save as much air as possible to extend your filters.
Stick to the shadows. To accompany the blue light, sticking to the shadows is the easiest way to get through Ranger Mode. Although you do more damage, using ammunition is something you'll want to avoid. You will only want to use your guns in situations where it is a necessity. Being on the surface is one of these places.
On the level "Bandits," you will have the opportunity to kill/knock out the entire level's enemies. In the beginning of this level is a merchant. If you choose to, you can pick up every weapon and every bit of ammo to sell. You will earn well over 1000 MGR, which also deal more damage to enemies.
Stick to one gun throughout. If you stick with one weapon throughout your play through, not only will you be able to sell all other weapons and ammo, you can use this ammo against enemies. Stick with the Kalash (AK-47), as its the only weapon that can use MGR as ammo. The Kalash is also one of the best guns in the game, as well.