It is older by a few years, but it is not a two-sided marketplace, it's Blizzard's (+ Activision's) DRM. FWIW, I did not mean that Steam is necessarily the lit

It is older by a few years, but it is not a two-sided marketplace, it's Blizzard's (+ Activision's) DRM. FWIW, I did not mean that Steam is necessarily the literal first game marketplace, but to my (limited) knowledge it was the first one that got large enough to become the "default" option.