Generally, movies based on video games are awful (there are exceptions - Resident Evil wasn't too bad). Just look at Lara Croft: Tomb Raider or the Super Mario Bros. Movie for example. Super Mario Bros. was particularly bad - dark and edgy setting, Bowser being a humanoid dinosaur rather than the dragon-turtle thing we know and love, Toad being a punk rock star, Yoshi being a veloceraptor, action-girl Princess Daisy and that's just five ways - there's probably more.
Based on this knowledge, we have ourselves a game on our hands. Basically, I will name a video game series and the next person will list five ways that it can be ruined by a movie. This could be by plot, characters, setting, anything really. That person names another video game series and the next person to post gets to name five ways that can be ruined. The same games can be re-used - five is barely exhaustive. Plus, it can be a game which a film already exists for. I'll do Metroid.
1) Romantic subplot between Samus and Ridley.
2) Space Pirates being depicted as rather literal pirates in space, complete with Kraid wearing an eyepatch and Mother Brain having a wooden leg.
3) Speaking of Mother Brain, she would be literally a brain who is a mother, always surrounded by her four Baby Brains.
4) Samus wouldn't wear her Varia Suit. No way. She would wear a new orange lycra catsuit in order to appeal to the horny male market, and it would be tighter than the suit in Metroid Fusion. Of course, the helmet, shoulder thingies and arm-cannon would still be there.
5) Samus would be a stereotypical blonde, finding Metroids "icky" and being totally clueless as to how to do a typical Morph Ball puzzle, only solving it by accident.
So here's what I would like the next person to ruin for everyone: Super Smash Bros.