I just made my first list and it is comprised of very long games including fallout 3, dragon age and mass effect and at this point contains only games I have played. It is by no means complete and I would like some suggestions from the community. The games must be both exceptionally long (preferably over 40 hours) and be single player experiences only (so no world of warcraft or modern warfare).
 
Edit - Online games now accepted! 
Also, a witty summary sentence for some of the games on the list would be appreciated, especially as I have never played some of the suggestions.