With Half-life as an example I feel that it adds to the mystery of Gordon Freeman. I think that the game works well with people talking about you or to you in the third person, though half-life is an exception as most games where the character can't speak it does reduce the immersion.

I've tried this before and can confirm that it definitely does work.

Right now, I'm really enjoying playing Resi 5 co-op, It feels as though that is the way it is meant to be played. I feel that co-op is one of the best ways to play a game, because you are working together with someone to achieve something. Great fun.

I got the achievement with only a few treasures in my inventory, so I would say that you don't need one of each treasure in the inventory to get it. Hope this helps.

To start with I was addicted to this game, but it got boring quite quickly as the gameplay got too repeatative