Killzone 3

So, as I mentioned in my last post I got myself a shiny new PS3 and some games to go with it. Gran Turismo, Tekken, Fifa, COD -all the usual ones. I quite enjoyed COD so decided to get another game in the same genre, the titular Killzone 3.
I get home, fire up the playstation and slide the game into the machine -so far, so good. I have a bit of a run around on the practise mode -hilariously entitled "Botzone"- after 10 minutes or so I'm starting to feel a bit funny. Not good funny, bad funny. As in "If I keep going I'm going to spew" bad.
Now I'm assuming this effect -a kind of motion sickness- is down to the fact that I'm old and a bit crap, but if that's the case, why didn't COD affect me the same way?
Does anyone else suffer from this, and if they do, is there anyway around it?

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