The Oregon trail (1971)

The gameplay is from the 1978 version, thanks to JMFSpike for the correction

The Oregon Trail is a computer game originally developed by Don Rawitsch, Bill Heinemann, and Paul Dillenberger in 1971 and produced by the Minnesota Educational Computing Consortium (MECC) in 1974.[1] The original game was designed to teach school children about the realities of 19th-century pioneer life on the Oregon Trail. The player assumes the role of a wagon leader guiding a party of settlers from Independence, Missouri, to Oregon's Willamette Valley via a covered wagon in 1848.

you can download the emulator here:

or
just launch the boot file and select the game with "j"

a great articles:

[JMFSpike]

According to the page you linked to, this looks like it's actually the 1978 revised version, not the 1975 one. Still, it's amazing that you managed to even find that one! It's surprising to see that It really hasn't changed much at all over the years. They literally just added graphics and made the hunting interactive. I've read that the later additions added fishing, but I haven't played any that came out after the 2nd one.