Call of Duty 4 is, and will be for a long to come, the best example of a game making me feel emotional. It was considerably shorter than a lot of games I've played, but I liked that because all of it was of such high quality. The pace of it was perfect, the characterisation was perfect, the gameplay was perfect, the game was just perfect. There was not one thing that I can think of that would have made it more enjoyable to play through.
So in answer to your questions, the things that made this such a good game for me were:
- Great storyline
- Great characters
- Consistently, and well paced
- The gameplay, obviously, has to be fun
- The ending is also very important
I've heard people say that they'd have preferred it to have been longer, but I'm glad that it wasn't. I think that it was so emotional, so snappy and perfectly balanced... I would have felt so into the characters and involved if the game if it had dragged on. It's like a longer, but not so good game with all of the filler taken out. Pure gaming perfection.