Holy shit!  I was doing the missions with John Marsden's son, Jack just yesterday!!  I pretty much figured the game was done.  I just took my son hunting!!  Why did I read this thread?  WHY!?

Haha, sorry. Don't you worry though, this has happened to me as well. Just a little late.

Okay.  I JUST got the ending and the true ending.  I read the O.P. in this thread and ruined the ending for myself (I thought I had already won the game and was just doing "Free Roam" missions.)  Literally, the very next mission was the one where Marsden died!!  How fucked up is that?  I put in so much time only to blow the ending!

Anyway, here's my take on it.  John Marsden's former gand did some bad things.  Unforgiveable things.  From that point on, they were going to die.  The U.S. Government used Marsden to achieve their goals but there was no way he was going to be forgiven.  I mean, look at the things he did before the game began--not to mention all of the fucked up things I did during the game!!  So, with all of the bad guys dead, the government boys tied up that one loose end by killing John Marsden.  He may have been repentant but life (and the law) doesn't work like that.

Why didn't he just escape?  Well, I figure that John was tired.  Tired of running, tired of fighting, and tired being used.  So rather than run off with his family and risk them getting kidnapped or killed, he took responsibility for his life of sin and went out in a blaze of glory.

I guess I'll go back for some Achievements but I didn't mind the ending.  I just wish it would have come as a surprise to me so that I could have felt the full impact.

I guess I should have put more warnings, unfortunately this game is like that, you never know when it ends.

Marston didn't deserve this though, because if he did then his son shouldn't have gone behind a retired lawman.

What his son did was exactly what John didn't want him to do. And why use him in the beginning? They could have killed him in the beginning or at the end of Dutch's death when he was alone. Just so that he could meet his wife? That would be too merciful. They also surrounded the horse shed at the end instead of the house, that's kinda funny.

It all seemed like R* wanted to end Marston to me.

I actually liked the game and the ending myself.  The game connected with me on a deeper level somehow.

I think its a great ending and the best single player experience of 2010.

So you mean to tell me there's a "true" ending as Jack? They really handled the end of this game poorly. Now I gotta remember who I loaned the game to.

I thought it was absolutely amazing. One of the best ever in the history of gaming. So obviously we have two different points of view on the story. After his death I immidiately did the "stranger" mission with Jack and killed him, the credits rolled, and I felt a feeling of closure and accomplishment like I have never felt in gaming before. I was emotionally invested, and felt torn down and rebuilt. The games story was as close to perfect as it could get. Asking for anything different would have been a huge let down. So sir, agree to STRONGLY disagree on this topic. 

1. The seeds were planted in Jack before John died.  Remember (even though I see how it could have been missed) when John and Jack were riding and Jack was talking to John.  Jack said he and John could be outlaws together.  He listened to Dutch and the others talk about their exploits when he was just a kid.  And first and foremost, John was his father.  The apple doesn't fall far from the tree.  Just like seeing his parents die could cause Bruce Wayne to wage war on all criminals, seeing his father dead at the hands of a merciless "lawman" after fulfilling his alleged obligations could make Jack seek revenge.  I mean, his mother only lived a couple more years (possibly died of grief).  Uncle died in that fight, too. 

2. Because Jack didn't really do anything.  He killed an old man.  John Marsten's story was much more epic.

3.  Maybe they felt he earned a little bit of a reward after he did the impossible.  Maybe they had to wait for orders from the higher-ups before just killing John.  Maybe, like the story said, they were saving John for the "next monster" they wanted him to kill.  With no monster, they decided John outlasted his usefulness and needed to be put down.

4. I don't know about you, but when I ran into the barn with John's wife and kid, there was still a lot of soldiers running around.  Maybe one of them said, "Hey, he went in there!"

Also, somebody mentioned that they couldn't take Fort Mercer without John's help.  I'm sure they could have.  They just figured, why risk our lives and the lives of our men when we can just make these outlaws kill each other.  Towards the end, when the allied themselves with John, maybe they realized, "Hey, this guy is pretty damned good.  We can use him." 

I thought the best of the endings would have been when Dutch died, yes. The nice slow walk back home with the music playing, a touching cutscene with his wife, and then final credits.

Like you, it took me a while to find the real ending. I thought "well, that's crap, I don't like this Jack Marston, and I want revenge!"

Admittedly, revenge was sweet. I did enjoy emptying an entire barrel of bullets into the FBI guy and shooting his brother and wife, but it still wasn't as good an ending as Dutch's death.