By now it is widely known that movies based on video games rarely turn out well. The reason for this seems to be a horrible series of coincidences regarding directors and material that don't seem to go together. Although the quality between films vary somewhat, albeit never above the 50% critical score on Rotten Tomatoes.
The highest rated movies, and the only movies with a high enough score to reach the 40s, are Final Fantasy: The Spirits Within and The Angry Birds Movie. Appropriate enough since those are some of my favorite game-based films, but what's interesting is that those two movies bared little resemblance to the games on which they were based. The Spirits Within was a completely original story in the Final Fantasy universe with characters who have never appeared in the games, and Angry Birds was based on a smartphone app so a certain amount of creative license is expected when adapting it to film. The lesson here is that creative freedom is the mother of quality entertainment, but these kinds of movies don't normally invite creativity because their very existence is seen as a 90-minute video game commercial. Why would filmmakers want to work on something like that?
Another problem is that filmmakers try to make their films too game-like, which leads to characters who lack personality and an overabundance of action sequences. The difference between video games and movies is oftentimes the reason why the translation from one medium to another rarely works. It's no wonder so many of them turn out so poorly when you consider all these factors.
So how do you fix the problem? Well, rather than give a series of rules for every game-based film, I would like to focus on a single movie that hasn't come out yet but is currently in the works as an example: Sonic the Hedgehog. There are plenty of ways for a film like this to go the "Ratchet and Clank" route and bomb horribly, but they can avoid that if they dodge some pitfalls, and I am completely ignoring the fact that they announced this movie as a live action/animation hybrid and that Deadpool director Tim Miller is producing it because this is an imaginary concept phase that has been untouched by Hollywood.
First, do not try to adapt any of the stories from the games, and if you do, be loose with the treatment. The stories in video games tend to be simplistic because it is the gameplay, not the story, that is the main focus. Probably for the best since Dr. Robotnik's evil plan to turn forest animals into robots leaves a lot to be desired for a feature film.
Second, never be tied down by the traits and personalities of the main characters. I know this will be hard for hardcore fans to accept, but if Sonic's character can be enhanced by adding new dimensions or omitting unlikable qualities, you should jump on this. You can't make an entire feature about a video game character. You have to change Sonic into a movie character who can stand next to Luke Skywalker and Indiana Jones.
Third, redesigns might be necessary - eyes are important when designing animated characters. Sonic's current eye design resembles a windshield, but it should look more like Mickey Mouse if you want the character to resonate with audiences. Probably not gonna happen, but that's the way I feel about it.
Finally, don't hire writers and directors to make this movie if they do not have a clear vision for what it should be. Sonic the Hedgehog deserves to be made with as much thought and care as Casablanca or The Godfather. All movies need heart, an interesting concept, characters who remind us of ourselves and a central reason for existing. If the director can't figure these things out, keep looking until you find one who can.
I am hopeful about the future of these movies. One day there will be a video game movie that is considered a masterpiece. But the way things are currently going, I would settle for one that's just good.