Single-player games very much existed before computers: puzzles, solitaires, etc.

See second paragraph. 'Basically all' may have been an exaggeration, but the crux of my argument is that the concept that human beings know as a 'game' up until the advent of computer games more often than not involved competition.

	▲	teamonkey an hour ago \| parent [-]
		Computers didn’t introduce the notion of solo play and there are examples of games throughout history that are not about competition. Archery, for example, has its roots in improving your skills for the battlefield. But archery as an hobby, which goes back as long as the bow was invented, is simply for the enjoyment of doing it. Kids playing together with toys is not a competition. Lego/Meccano/building blocks. The list goes on.