Soundwave on 19 March 2014
Nintendo with the Wii ... like it or not, it definitely disrupted the marketplace and changed how people viewed video games. XBox 360/PS3 honestly just were straight forward iterations on the PS2/XBox, which isn't a bad thing, but they basically were just the next natural step.
XBox Live and Playstation Online was already well underway 10 years ago, so it can't really even be that.
