I have a ton of games I have bought and started but never finished, for both PC and consoles - some of the highlights include MechWarrior 3 and 4, Fallout 3, Mass Effect, World in Conflict, several GTA games, and almost everything I have bought on sale at GOG or Steam. I have started almost all of them, and enjoyed them, but never seem to finish them. I finish very few games that I buy. I can honestly think of only a handful of post-Atari games I have played all the way through. ON PC, it is Crimson Skies, Command & Conquer 3, C&C3: Kane's Wrath, Battlefield: Bad Company 2, and just last month, FSPort. For Xbox (the original, not One), it was Crimson Skies: High Road to Revenge, MechAssault, and...yeah, that's it I think.
I try not to be a perfectionist, but something in my psyche wants me to do everything "right" the first time through. (In RL, I certainly am not a perfectionist!) That means no failures or missed objectives in any sort of linear campaign. If there is an obvious secondary or bonus objective, I want that too. I think that is what kept me from finishing FS2 when I bought it over 13 years ago. I played for hours, but got frustrated that I could not finish part of it. It may have even been the same mission I just finished (with cheats). http://www.hard-light.net/forums/index.php?topic=87167.0;topicseen
I have similar issues with RPG or open-world games - I don't want to miss anything, so I try to do all side quests and get all equipment and finish everything, but sometimes it gets tedious and I quit. With racing games I want all the cars and all the upgrades and all the tracks, but it can turn into a chore instead of fun.
Fatherhood/family life has added a new set of challenges. I usually don't game while the kids are up, but when I do I usually don't play things where resuming from an ill-timed "pause" can cause issues, such as in racing games. It also makes it hard to play RPGs where I need to pay attention to what the characters are saying while the wife unit is talking to me as well. I tend to play slower-paced stuff like C&C3, and usually I do skirmishes rather than replaying campaign missions.
The end result is that even though I enjoy the games, I end up rarely finishing one.
Another thing that seems to be getting worse as I get older is that I don't want to learn new control schemes. That was part of what kept me from coming back to Freespace for so long - it was more complex than W-A-S-D and mouse with a couple of buttons. I'm still struggling with keyboard commands and adjusting joystick bindings, and I probably won't do any other flight games or mods until I finish this one. For instance, in Diaspora I had the hat switch mapped to thrusters to assist with landing, but right now I have targeting functions mapped to it for the main FS2 campaign, and I had the glide function mapped to a joystick button that I am currently using to equalize shields.
No point to this, just wanted to share my thoughts and see if anyone has anything similar they want to share.