Live service games face an interesting conundrum, I think: how do you keep offering the core experience of a game while also periodically reinventing it, and varying it, in such a way that will make it feel new? Overwatch is a game facing such a conundrum, and Blizzard has tried all kinds of different things to mix it up: switching to five-person teams from six, developing a PvE mode that never materialised, and for the past year or so, offering…