I can never finish a game

I have the same problem and this is why I do Let's Plays on YT. Some people may judge me for that (nerdy, dorky, annoying, whatever) but honestly it's been the best way for me to commit to getting a game finished. People who watch me expect me to finish it so I'm held responsible lol. Not to mention it give me practice in speaking on the spot which I'm really bad at ._. It's only because I LPed Kingdoms of Amalur that I finished it. Even then it took me a ridiculous 2 years to get through it (not playing continuously of course. I just took such long breaks from it). I'm sure I would have quit within a couple hours otherwise.

I finish all the games I start, unless they are repetitive and the gameplay is not at least decent, but yet again, I only play a SP and a MP game at a time. The thing is that I don't really start playing new games.

First world problems xD.
I also have the same problem as you, rather than forcing yourself to finish that one game which might be repetitive, you should take a break from that certain game for a while and play others. One day you might be in the mood to continue playing the game.

its been like that forever for me. Heck, Final fantasy VII is probably the last game i finished and it took me like 3 winters to finally complete it !!

i think in my whole life i completed like 3 games, Fallout 2 , Final Fantasy VII and Super mario bros 2 or 3 (one where you can get a flute to skip 4 worlds ! :D) and well, thats about it (:

Happens to me as well, though as of late, I've become better at actually finishing games, once I've committed a bit of time to them (I quite often drop games early on though if I see something else that looks nice and shiny)