I was reminded that a long time ago in Ahoy magazine, there was a dual-screen two-player adventure game published. By dual screen, you and your opponent would need two, separate monitors -- one for 40-columns and another for 80-columns. Authored by Cleveland M. Blakemore, the game was called Dark Fortress and was in Ahoy, issue 37. The magazine article plus instructions is at
I’ve been thinking about this ability to make like a card game where you can’t see each other’s cards because they are displayed on different screens. The Dreamcast had its VMU memory cards with displays where Sonic Shuffle used that to display each player’s own cards. Pretty neat feature.