[StarSlayer]

If by finish finish the primary story arc and most if not all optional side missions then I finished a good majority of games I started.  If by finish you mean get a hundred percent of the cheevos then no.

[AdmiralRalwood]

I rarely 100% a game, but I do try to finish every game I start. There are a couple noteable exceptions to this, however, even among some of my favourite games. For one, System Shock 2. I've gotten very far in SS2 multiple times, but at some point I wind up being distracted, or my co-op partner gets busy, or what have you, and the save file is neglected. If I ever come back to it, I forget what I was supposed to be doing, don't like my character build, whatever, and wind up just starting a new game. That, or mods update and I need to re-do my installation and don't keep the old save file because it now relies on an older version of my data. Now I have a recent save file that's on the Rickenbacker and with a character build I like and none of the mods it relies upon have updated recently... but the computer it's on is currently inoperable. :/

Another one: Morrowind. Despite spending thousands of hours playing that game, I have never played through the main quest. Mostly due to constantly-shifting what mods are installed. I think the farthest I got was being declared nerevarine by the Ashlanders before (of all things) that save file became unusable. To be more precise, that Morrowind install started BSoDing every time that save file was loaded. Real pain in the ass. I finished Oblivion and Skyrim within days of their release, but Morrowind remains in my "unfinished" category. On a slightly-related note, I finished Fallout 3, but only three of the DLC, and didn't even start the other two, and never finished Fallout: New Vegas (or started any of the DLC).

On the other hand, there are some games I do 100%. I got 100% in Castlevania: Dracula X Chronicles, despite the massive annoyance of clearing Full Boss Rush no fewer than three times. I 100%-ed both Castlevania: Aria of Sorrow and Castlevania: Dawn of Sorrow, unlocked everything on the PS2 version of Devil May Cry 3 (Special Edition), and went out of my way to view the secret endings in Kingdom Hearts, both 1 and 2. Currently, I'm trying to 100% the HD remaster of Final Fantasy X. Pretty close, too; got only two achievements left, and I'm most of the way towards getting one of them, and then I just have to beat the toughest superboss in the game.

[SypheDMar]

This thread reminds me of this:

http://www.gametrailers.com/videos/ur6ce9/the-final-bosman-nobody-finishes-video-games  (Just watch the first six minutes)

I don't 100% most of the games I play (with the exception of Super Smash Bros. Melee and FreeSpace)

[Sarkoth]

I generally used to finish and 100% complete any game I had. I even was a die hard achievement and trophy hunter for about 3 years, doing ridiculous BS like grinding relentlessly for weeks (and sometimes even months) for certain multiplayer badges / ranks / killcounts.

The craziest thing I did so far was getting in the top 100 for the Killzone 2 weekly multiplayer ladder for a particular badge. Took a week of vacation off from work just for that, playing 8 hours a day for seven days straight.

And at some point I stopped, looked back and thought "What the **** am I doing here?". Gaming had become some form of tedious work. Before I even started any game, I would look for collectible guides, look up missables and would completely plan out the minimum number of playthroughs needed. At some point, that stopped being fun. Although sometimes, the lines do get blurry. For example, I still read every wikia article about any Skyrim location I visit, to not miss out on any quests, npcs, treasure and bugs that might have to be accounted for. And I play Skyrim by systematically exploring the map, raiding dungeons in bigger getting circles like a sawm of locusts.

Then again, I started dropping games, when playing them wasn't fun anymore. I still play 95% of the games until the end, but if I do get annoyed too much, I just drop them and forget about the 100%. Not that is helps much in regard to my backlogs.

My current backlog from GoG.com alone is 120 games, sitting at about 150 total for PC.
My PS3/PS4 Backlog is at around 60 games.

Most of those 200+ being RPG games that can take 50h+ each.

Right now I am already feeling successful if I can keep the backlog at a steady number without it increasing. Chances are, that I might have to drop some games completely without ever having them touched.