I mentioned DTSS's userbase for a reason. Every single Dartmouth undergraduate student from 1968 onward wrote BASIC programs during a required mathematics class. Every Dartmouth student and faculty member was free to log into DTSS at any time from hundreds of terminals scattered around campus, plus hundreds more off campus at high schools and colleges in the northeast US. This drove an incredibly high usage for both school and fun among Dartmouth people (yes, including games). Nothing like this existed anywhere else on Earth in 1968, and was still rare 20 years later.