FINISH HIM

If you play a game part of the way through, but for some reason you just dont finish it, or say you make it to the last stage or boss fight or whatever and quit because its frustrating or too hard yet you enjoyed the game up to that point, will that one situation sour your entire opinion? Would you have given the game an 8/10 but because of not finishing it, you give it a 4? What if you just dont finish it because of real life business and when you return to it, you just cant get back into it?

Also, mentally do you "let go" of a game, consider it finished, if you never beat it? I have a hard time with that. I never quite let go of a game I dont finish and it constantly nags at me while im playing other things. I wish I wasnt so obsessive about beating games, because to be honest I dont have a stellar track record of finishing games the past several years. I think its a holdover of having tons of free time/energy when i was younger and always finishing them. How about you guys?