My take:
- the old man would be a grizzled, scarred, former paramilitary bad ass,.. still old, but kicks tons of ass. Smokes cigars, is found in a strip club, carry a gatling gun in his back pocket
- the fat kid would be a hot 18 year old Asian girl,.. who is into computers and knows how to kill
- the house would be an air fortress,.. which was made from the strip club we found the old man
- the bad guy would be young asshat, who gets sodomized by the dog towards the end of the film
- the dog would be as is,.. except for the sodomy thing
And, of course, explosions.. even during the sodomy.