There are lots of ideas, my personal favourite is having to take two players off every five minutes. Once you've got that much space with tired players they'll soon be a goal.
But, it'd be no fun for the rest of the world.
England would have won the World Cups in 90, 98 and 2006 along with the 96 and 2004 Euros if there wasn't penalties, and I know there's a lot of you out there that don't want that