Fallout 3 karma achievements and trophies

 are achievements and trophies which require you to have either bad, neutral or good karma upon reaching levels 8, 14 and 20. Each one is named for the title you acquire upon reaching the specific level with the specific degree of Karma. Additional karma achievements can be unlocked at level 30 after downloading the Broken Steel add-on.

Good Karma

 * Protector (level 8)
 * Ambassador of Peace (level 14)
 * Last, Best Hope of Humanity (level 20)
 * Messiah (level 30) - requires Broken Steel add-on

Neutral Karma

 * Mercenary (level 8)
 * Pinnacle of Survival (level 14)
 * Paradigm of Humanity (level 20)
 * True Mortal (level 30) - requires Broken Steel add-on

Bad Karma

 * Reaver (level 8)
 * Harbinger of War (level 14)
 * Scourge of Humanity (level 20)
 * Devil (level 30) - requires Broken Steel add-on

Glitches

 * On PS3, the trophy icons for True Mortal and Messiah have been mixed up. True mortal shows a "Jesus" like vault-boy
 * On PS3, using the scrap metal glitch to gain XP sometimes doesn't get you any of the bad karma trophies.

Strategies
It is possible to get all three karma achievements/trophies for each level in a single play through of the game, by saving the game just before you gain the level (levels 7, 13, 19, and 29) or even two levels before if you use the Here and Now perk (levels 12, 18, and 28). Use one of the strategies below to change your character's alignment and level up, then reload the original save game. The achievement/trophy will stay on your account. Also, keep in mind if your karma is neutral, then any of these methods work to get you to become good or evil (Just remember to save your game before doing so if you wish to keep current karma).

For "Fast-killing" you need to use the Fat Man or Experimental MIRV. After you summon characters, shoot to the ground - they will surround you, and this is good way to kill them all. Until you get karma title's, level's and of course, achievements. If information about acquiring the achievement doesn't appear, you should stop shooting, and enter Pip- Boy and then, wait for while(or press HOME key and then wait). If achievement doesn't appear reload last save. It better if you quicksave the game after acquiring the levels, 'cos the game can slow down your computer performance or crash from overloading memory. And important note - G4WL doesn't connected with game fully and you can use codes like "tgm" to do this and achievement's won't be blocked.
 * As an evil character, donate caps to a church (1 cap raises your karma by 1, so a max of 1250 caps is required) or give purified water to a beggar.
 * As a good character, slaughter a town (1 murder lowers your karma by 100, so a max of 13 kills is required)
 * As a good character, access an owned terminal and close it, rinse and repeat (counts as stealing, so a maximum of 250 times is required, making this method very time-consuming). However, wall-mounted terminals can be activated multiple times in quick succession while the keyboard unfolds.
 * As a good character, if you haven't killed Paulie Cantelli in Rivet City, then give him as much Psycho as you can. Each Psycho you give him results in a loss of 100 karma.
 * If you have the Broken Steel DLC, you can get the final karma rewards much easier by taking the Escalator to Heaven, Devil's Highway, or Karmic Rebalance perks to set your karma to good, evil, or neutral, respectively. So make sure you have a level 29 save right before you get the Level 30 Level Up. Use the 2 that are different from your current karma, and then get the last one using your current karma and take whatever perk you want. (ex. You are Very Evil. Take Escalator to Heaven, reload Level 29 save, take Karmic Rebalance, reload Level 29 Save, and continue to play with your Evil Karma for the last trophy/achievement upon leveling up for the last time). (Even easier if you have never taken Here and Now. Save before hitting level 29. Take Here and Now to reach level 30 and choose one of the three good, evil, or neutral reset perks. Rinse and repeat.)
 * There's also the "fast" way to get the achievements for the PC version users. All you need is: get/equip the Fat-Man(base ID 0000432C) or Experimental MIRV(base ID 0003422B) and ammunition(base ID 00020799) via console command ("player.additem base_ID_weapon_or_ammo"), type command "tgm"(This is code for immortality, but you should enter it), and get to quite and clear place. And then:
 * 1) For evil or neutral character to gain a good karma: It is necessary to kill a evil character - for this summon Alistair Tenpenny (base ID 000156e0) via console(command "player.placeatme 000156e0 X" where X is a number of Tenpenny's that you want to summon and... kill them until you get good karma title (for your level). Then summon a monster, like Super Mutant Brute("meele" version, base ID's 3A148/94EC8/9E8E0) until you reach 30 level.
 * 2) For good or neutral character to gain a evil karma: It is necessary to kill a good character - for this summon Cherry(base ID 0002ae21) and do the same thing as before, but for evil karma(and evil karma title) now.
 * 3) For neutral characters - kill only Super Mutants Brute's