Over the past 12 years, the Swedish company Paradox Interactive has developed a stable of grand-strategy games for the PC that simulate with often baffling complexity the political, economic, and military maneuverings of entire nations over the course of centuries. Paradox's titles, including 2004's Crusader Kings, are fascinating and fun if you can understand what's going on, but getting to that point is often a long process. Crusader Kings II - released in February - works hard and largely succeeds at being more accessible to novice players while retaining immense depth for those looking for it.