The opening montage (if that's what you would call it) would be the most likely cause, I certainly teared up and my girlfriend cried the second time too. Frankly, if you're not moved by that sequence then you might be playing too many video games! It was tragic. If not then, perhaps when Carl finds Ellie's adventure book at the end.
I just thought this would be a good place to ask this question, as people generally consider gamers to be desensitised to such things!
I just thought this would be a good place to ask this question, as people generally consider gamers to be desensitised to such things!