Video games are hard because of the game in itself. Take a perfect example of a game hard to turn into a decent movie (streetfighter) the way Hollywood has messed this up in the past is to try and fit all the characters in. Making shit cameos and terrible introductions.
Whereas take an average marvel movie and it is about one hero and many times, one villain. Much easier to write since there is one story to write instead of 12.
Then you have the way to do it “right” such as the news streetfighter movie. Concentrating on only ken and ryu and gouken and Akuma.
But that formula pisses off this characters fans and that characters fans that weren’t in the movie… Creating possibilities of sequels, but still a formula that still leaves some people out in the cold.
And finally what about the games that have one protagonist? Most are kiddy heroes like sonic, or Mario, Rayman, crash bandicoot, etc. tomb raider “worked” because it is about one girl, not a huge assortment of people.
And the others that are one protagonist could definitely work, like dante, or bayonetta are perfect examples. Even kratos.
At the end of the day, what is needed is money and the ability to tell a “dark” story like the batman and superman reboots, or a “light” story like wizard of oz when it goes color after Dorothy lands, or like in Thor 2.
And finally besides the points already made the BIGGEST reason why it’s easier for comics to be introduced to movies than it is for video games is because comics are story driven whereas some games very much are not.
All that needs to happen is the proper money be thrown at the right project and the people in charge of the project knowing the key points of how to make a good actioner.
Transformers as an example keeps the number of robots that take center stage, to a minimum to keep the movie able to have some depth of character in getting to know individual robots rather than see a ton of them and know none.