I noticed something similar with flight Sims. After Falcon 4.0, they kind of disappeared until recently with DCS. Space Sims disappeared too until the X-series. Now we have possibly the greatest one ever in Star Citizen/Squadron 42. Around $55 million raisedb- and all we have is a playable demo of a few ships.
I think a kickstarter could do well - look at Warhorse studios Kingdom Come - a non-magical medieval RPG. As long as the word got out, but I haven't the faintest idea of how much of a budget a modern WWII subsim would run - obviously in the millions or tens of millions.
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