Twenty-one years ago, Roq La Rue Gallery opened its doors in Seattle, and a new group show at the space, “Ace Of Spades, Queen Of Diamonds” offers a window into that history. The line-up is considerable, and owner Kristen Anderson says it’s “by no means comprehensive, given how many artists we’ve exhibited over the years, but it still represents a nice little microcosm.” The show runs through Sept. 6 at the gallery.