I agree with Randy Smith though that many games are too artificially long these days. Never finished Mafia 2 for instance because it was such a drag (seriously, driving 10 min long to a destination and then distributing cigarettes? WTF?)
Trim the fat of these 12 hour campaigns down to maybe 5 hours and make every single minute exciting and memorable.
RPGs might be an exception due to their structure and storytelling, but as for action games, they indeed wear out too fast.