Wander the streets of Paris, Tokyo, London or pretty much any other city, and you’ll notice Invader’s tiled homages to the pixellated characters of video games from the ‘70s and ‘80s. Since they started springing up in 1998, they’ve appeared everywhere from a Bhutanese supermarket to the Hollywood sign, with the aim of bringing art out of the gallery and freeing space invaders from the screen. Collectors can invest in...