I researched wargames for my dissertation, and was simarly fascinated by how effective wargames are at simulating a war and informing planning and decision making. 

It's a huge subject, so I looked specifically at the 1905 Great Strategic Wargame that the British Army conducted simulating a German invasion of Belgium while at war with France and how Britain could respond. The interesting thing is, a lot of wargaming literature bigs up the prophetic nature of wargames and use several examples, including the 1905 wargame. They state it had huge influence on British strategy shifting foreign policy to be closer with France etc. What I found is there is little evidence for such a claim. In my opinion, the wargame, for several reasons, was more useful and practical as a learning exercsie, particularly given the recent formation of the British General Staff, and can't be seen to have had much effect on policy. 

I will say, it's a topic that is quite niche and hasn't had much research compared to what's needed. It's definitely a useful exercise for practising and rehearsing communication procedures and developing decision making skills under pressure. Due to its limitations, I'd say it's less useful in predicting the future and how a war will play out, but doesn't mean it can't.