Organ Trail is a zombie homage to the classic Oregon Trail game. Amidst a zombie outbreak, a small band of friends grab a station wagon, stock up on supplies and hit the road in an attempt to reach a safezone all the way across America.

The description on the official page is pretty amazing:

Organ Trail was an edutainment game developed in 1971. Schools across America used this game as a teaching tool to prepare children for the impending zombie apocolypse and dysentery.

Re-live your childhood with this faithfully emulated version of Organ Trail for the Apple-II.

Indeed. It's all very silly and good fun. Go play! [Source]