A few things. First, treating the world as it is presented in the game. Don't move the Mario Bros to New York or make a Final Fantasy film without chocobos or summons.

Second, the the focus of the movie should not be the plot, which will usually be to get the McGuffin and Save the World. Video games are inherently power fantasies in a lot of respects which is why their plots tend to be paper thin. The drama comes from playing the game, not the beats of the story. For a movie you need to shift that around a bit. This is easier said than done, but it is solved by...

Giving the characters actual depth and development as they face the challenge in front of them. There is lots of fodder in games for this. The relationship between brothers in Devil May Cry. The struggle of a barcoded Hitman for a unique identity when he spends all of his time pretending to be someone else. Or consider that Link has never met Zelda in the original game, and yet he must travel the land building the Triforce of Wisdom in order to stop a tyrant wielding the Triforce of Power. You can reap deep themes out of that, a young man dreaming of being the powerful hero, desiring to be strong of body when it is strength of mind that will help him overcome his foe.

The moment you decide to turn a video game into a movie you have to drop the idea it's a video game movie. Otherwise we get crap like what the upcoming Hitman movie appears to be, a producer's idea of what a video game movie should look like, with lots of explosions and crappy one-liners. Christopher Nolan didn't make a great comic book movie in the Dark Knight. He made a great drama where the characters all wear masks, inside and out. It was simply based on stuff that started in a comic book.

It can be done, but it takes knowing how to translate the settings and themes into a new medium without betraying what they are all about.