Bad collision detection with respect to the character appearance, and the game not being understandable if you didn't thoroughly read the manual.

http://www.neocomputer.org/projects/et/

When I was six, a cousin about to leave for college gave me his 2600, my first console.

With it came not one, but two (!) copies of E.T. So I had a backup in case I accidentally dropped one in a pit or sinkhole…

Or double the pleasure of intentionally throwing it in a pit or sinkhole...