I’ll start with the premise that any culture dominated by young males is going to be toxic, for both mature men and women and especially for young women. I can’t think of any counter-example in the history of the humanity.
So, if we want to make the culture of gaming more young-women friendly, we need to eliminate the young male customer base. Traditionally this is done by sending them to war to die in large numbers or putting them to menial work so hard they don’t have the energy in the pittance of leisure time permitted them.
However, society has (thankfully) changed. Instead of destroying the supply of young males, we need to destroy their desire to be part of the culture. The simple answer, eliminate all the aspects of gaming that appeal to young males. And the quickest answer to that - eliminate the attractive forms of violence and sexuality in games. Have the government ban them.
Bereft of the sex and violence that attracts this demographic, they stop buying, and the market collapses. With AAA titles all dead (and probably the consoles as a whole), the independents (of whom there are quite a few now), suddenly become visible.
The dominant culture morphs and games are now seen by all as acceptable (albeit economically and socially irrelevant).
I don’t, however, have an answer for those who like violent video games, but not the type of people who are generally attracted to them. I’m not certain how you separate the wheat from the chaff. It’d be like wanting a social aspect to hard-core pornography, but not wanting to deal with the creeps.
(In fairness to young males, it should be noted that probably only 10-20% of the young male are highly problematic. However, they’re inseparable from the demographic as a whole (and they’re constantly going into and out of problematic phases), so the whole demographic has to go. Apologies to my sons.)
As an aside, isn’t this more or less what happened to comic books to make the industry at least somewhat more female-friendly? Based entirely on personal experience, the last time I visited a comic book store it seemed (1) much emptier (2) far harder to find (3) much more evenly split between male and female customers (4) diverse in terms of content (5) vastly more pleasant - none of that slightly grungy elements (stores, customers and staff) I associate with comic book stores in the 80’s.