Rejoice all ye evildoers and bad-karma-nators! If you've ever done something you're not proud of and feel guilty about then fear not! All you need to is to write what you did in the comments section here and you may be forgiven! I myself am not without bad actions and so for Fallout 3 I will list off the bad (or questionable) things that I did.
1. Insulted Butch's mother for her predisposition towards alcohol
2. Blew up Megaton
3. Slaughtered the Family
4. Enslaved Bryan Wilks at the end of Those!
5. Killed the Ghouls for the Tenpenny Tower quest
6. Completed Strictly Business by enslaving all four individuals
7. Sided with Zimmer in the Replicated Man quest
8. Sided with the Mechanist and allowed him to continue his superhero fantasy
9. Sided with Ashur in the Pitt
10. Killed Amata's father at the end of Trouble on the Homefront
11. Killed Sydney for her fabulous SMG
12. Sided with the Slavers in Head of State
13. Completed You Gotta Shoot Them in the Head by killing the people except Tenpenny
14. Killed Agatha after delivering the violin
15. Made Paulie Cantelli overdose on psycho
16. Enslaved James Hargrave's mother
17. Allowed Mister Lopez to kill himself
18. Caused Mei Wong to commit suicide
19. Gave the Necronomicon to Obadiah for money
20. Left the three Little Lamplighters in the Paradise Falls pen
21. Killed Anna Holt in The American Dream when I found out she betrayed my father
22. Enslaved other Wastelanders for monies
23. Told Button Gwinett that America lost the war of independence to Great Britain and said that he was a disgrace
24. Eaten several corpses with the Cannibal perk
25. Slit Timebomb's artery
26. Sold Bumble as a slave
27. Followed all of Doctor Braun's orders. Would you kindly?
28. Shook down Macready for all the cave fungus he was carrying after threatening to blow the cave.
29. Blew up (a somewhat large part of the Earth) with the deathray on the alien ship.
30. Gave all the Quantums to Ronald.
31. Blew up the Citadel with the nuclear payload.
32. Lit Fawkes on fire in his cell.
33. Reprogrammed Cerberus to attack the non-human ghouls. Come on, it's somewhat fitting if you think of another series!
34. Infected Project Purity with Eden's virus.
35. Shook down Winthrop for his stuff after threatening him.
36. Sent in Sarah Lyons to the Purifer chamber.
37. Made Butch beg for his mother's life, only to leave her to die anyway.
38. Made James Hargrave run away from home.
39. Have sided with the cannibal folk of Andale.
40. Burned Harold.
41. Left Big Town to fend for themselves.
42. Gave FEV laced water to beggars for the lolz.
I've only given Fallout 3 examples but feel free to do any game you want, or combine. And just remember, if you don't feel entirely forgiven after what you've done, you can always just give water to beggars or donate to the Church with your blood money...