Whenever you start playing it with the intention of simply having a short blast at the Covenant, invariably turns into an official Blow Shit Up day.
In other words... once you start playing, you can't stop.
I'd finished the first level and was about five minutes into the second when my mother decided to join me.
We're now on the Silent Cartographer - accidentally renamed as the Lost Archaeologist - with very little in the way of intentions of stopping.
Master Chief~~~! *fangirls*
Gods I love Halo.