Face it: if you pay $15 for a movie ticket and $60 for a video game, you expect the video game to have some competitive, original content.
For DC, big video game plot twists aren't unprecedented, either. The only thing is that, as fans, we'd need the Suicide Squad game's story to remain true in the future - for the movies and video games that will inevitably grow out of the new DC film universe.
Example: don't kill off Harley Quinn in the Suicide Squad game if that type of thing won't fly in the movie universe.
But what if Deadshot accidentally witnessed Bruce Wayne's parents being murdered years ago? That's more like it.