Scramble isn't vertical either.
1941 needs an 8 way stick and I suggest you put one in or you will miss some great games ( or at least a switchable stick ). Personally I would skip the trackball for your project unless you are a huge Centipede/Misssile Command fan.
Also QIX, Time Pilot, Alpine Ski, Bomb Jack, Juno First, Phoenix, Moon Cresta, Tetris, Donkey Kong, Donkey Kong Jnr, Pleiads some of my favourites but there are plenty more.