X-Wing and Tie-Fighter. Man they would be awesome with today's graphics.
And all of the Ultimas, Oblivion or DA:Origins style, with updated dialog on the older ones (U7 doesn't need it).
Also, as someone already posted, PONG. In 3D. With RPG elements, ah ha ha
There was this game for the Atari 800XL, cannot for the life of me remember the name, but it was split-screen Multiplayer in first person where you were on a huge checkered board and you had to grab a pulsing orb and get past your opponent and shoot it between two goal posts that moved and got smaller as you got higher scores - probably my first ever experience with playing against another person and so awesome in its simplicity of gameplay yet so hard to stop playing. Anyone remember what that was called? I *think* it was a Lucasarts title.