Metro 2033

This is how I managed to get both endings and the Ranger Easy / Ranger Hardcore achievements in one playthrough. Not 100% sure you have to do all this, but this is what I did.

1. Download the DLC before playing the game or starting another playthrough.

2. You can choose Easy difficulty (doesn't have to be Ranger Easy or Hardcore).

3. Trigger the Enlightened ending. See 2nd edit below.

4. At the end of the game decide which ending you want. You'll either get "If it's hostile, you kill it" or "Enlightened" depending on what you decided to do.

5. After the credits, back at the title screen, choose to continue.

6. Go to options and change the difficulty to Ranger Easy, make sure you save and exit and then quit to the title screen.

7. Choose to continue again (go to options and make sure you're on Ranger Easy) and play the last part of the game again but trigger the opposite ending you did in step 4. You should now get the other ending achievement AND "Survivor" for completing the game on Ranger Easy.

8. Repeat from step 5 but choose Ranger Hardcore this time. Make sure you trigger the first ending you did again. It doesn't work if you use the same ending twice in a row.

EDIT: If it doesn't work the way I've described you may have to dashboard to get it to work as mentioned in various comments below.

EDIT: Some people haven't needed the enlightened ending and were able to use the bad ending twice in a row. Originally when I tried this, it didn't work for me that way. I had to switch endings to get the other achievement but there may have been a game update or some other variable in your playthrough that changes this.

If you have the original 1000G and just need the DLC achievements, you'll need to start a new game with the DLC installed. It means another playthrough but you'll still be able to get Ranger Easy / Hardcore achievements in the same game.

My main piece of advice for this achievement would be to make sure you keep a very close eye on your gas mask filter count, as they deplete a lot faster in this mode than in any other. I struggled through 2 or 3 gas mask sections with inadequate filters, and it was a massive hassle, at least twice I had to reload an earlier level (For the record, loading up an earlier level will not affect you unlocking this achievement, as long as you don't change the difficulty.)
Also, when it comes to the Library, just run for it, I didn't bother with any kills, and finished the section with zero problems.
For general combat, nosalises aren't too much more difficult than usual, but bullets from other human enemies hurt A LOT more, so extra care is advised.

Good luck to all on the path of the Ranger!

EDIT: So everybody knows, the Ranger Easy and Ranger Hardcore achievements ARE NOT stackable (Thanks to Scion Racer.)

The glitch on the other guides never worked for me so I had to complete the game properly.

Heres a few things I found useful on this difficulty.

On the level "lost tunnels" pick up the volt driver and keep it until you reach the level "market". When you reach "market" go to the weapon merchant and trade the volt driver for the automatic shotgun. The trader will give you a refund of 147 gold bullets. Use these to buy air filters for the gas mask. You should get between 7 and 10 filters for 8 gold bullets. Get the maximum of 44. These are very important later on in the game!

On the level "armory" you need to buy two things. First is the VSV with a scope. This weapon also has a red dot sight and a silencer which helps on the next level "frontlines". Second you need to buy the heavy suit from the guy standing opposite the weapon merchant for 100 gold bullets. This armour resists damage and will keep you alive later in the game when you are surrounded by enemies.

When you reach the level "polis" Theres a gun merchant sitting next to the guy who sells bullets from a kiosk talk to him and buy the kalash 2012. This weapon has everything the VSV has but with a 40 bullet clip. At this point spend the rest of your gold bullets on various standard rounds for all your weapons.

Finally to preserve your gas mask filters keep taking off your mask when a NPC is talking. You can survive for 15 to 20 seconds without it. You need to put it back on when the screen turns black and white. This is extremely helpful on the "D6" level when the NPCs talk for ages.

Hope these tips help.

This can be a very frustrating achievement at times, but it isn't extremely difficult with patience and a good beat to keep you going. There aren't any true patterns that will work specifically for everyone, so I will just highlight a few important practices while trying this.

- All ammo clips will only give you a single bullet or sometimes slightly more. You will be forced to use your ammo very sparingly and only shoot when you absolutely need to.

- The AK is your best friend in the whole world. On this mode, this will kill many things in only a few shots. This ammo is pretty expensive though, so use it wisely.

- Prior to attempting this, try to get achievements for collection, like "Find all ranger caches in Dead City 1 and 2" and "Sherlock" for finding the golden bullets. Memorizing the locations to these stashes will be invaluable to you.

- At any time you can exchange your ammo, trade in all of your Helsing Arrows and the Pneumatic rounds for money. If you don't use shotguns often, trade those in, too. The ONLY thing you want to actually want to buy is AK ammo.

- The filter and gas mask issue doesn't usually prove to be a problem, you just need to remember to work fast so it doesn't wear out.

With these highlights, you should be able to complete Ranger Mode Hardcore and do it again on Ranger Mode Easy. I hope this is useful!

If you're looking to do this legit, like I did, I have a few tips you'd do well to heed.

1. Play the game on Easy (not Ranger Easy) and follow the walkthrough provided on this site. Not only will you wind up with most of the achievements by the end, but you can also explore and familiarize yourself with the game without too much frustration. Better have a good memory, though because you'll have to think ahead a few steps during your Ranger Hardcore run.

2. Stealth, Stealth, Stealth. I cannot emphasize this enough. When facing human opponents, do your best to sneak around them. Sometimes you will have to engage in which case I would recommend going all Assassin on them. If you're having trouble with a certain segment, there's a guy on Youtube who did a Stealth run on Hardcore and has some good tips.

3. RUN! This game has a good balance of human and mutant enemies. However, this also means that Stealth is often not going to be an option, as it is impossible to sneak around mutants. As such, if you are supposed to go through a mutant infested area, just sprint. This is why it's so important to have played the game through already. Cursed Station has infinitely respawning enemies, and the Library has all those Librarians, so running past them all is the best way to handle this.

4. Use the AI. I don't understand how people can say this game has some of the dumbest AI, well, maybe the mutants are stupid, but anyway... So on occasion you will be put in a hoarde scenario where you need to defend against waves of mutants. In this situation, get behind the AI and crouch down in a corner. The mutants will mostly go after your AI partner, making hectic situations, a lot more manageable. The AI partners are invincible (except in scripted deaths), are really efficient at killing mutants, and don't ever seem to have to reload, so making them the center of an enemy's attention is highly beneficial.

5. Manage Your Loadout. If you know you're going to be facing mutants soon, find yourself a shotgun, as this is the most effective weapon. For stealth, I recommend the Helsing or the VSV sniper rifle, though you shouldn't combine them. After Black Station, stealth will no longer be an option so you won't have to worry about silent fire.

So there you are, follow these tips and it'll make this achievement a lot easier. Good luck.