watchmen_rpgThere’s not much on the Watchmen tabletop gaming scene:

In the late 1980s, three Watchmen supplements to the now defunct, but still well-regarded, DC Heroes RPG were released: “Who Watched the Watchmen”, “Taking Out the Trash”, and the Watchmen Sourcebook. These included adventures and scrap material from both Alan Moore and Dave Gibbons. There was also a complementary set of metal minis. (source)

Aside from this, you can find a few novelty game accessories, such as these Watchmen playing cards.