Let's begin with the seemingly innocuous hazards. First of all, as a video game designer you'll spend an amazing number of hours plopped in front of a computer screen. What will that do to your body? Let's start with the 10-15 pounds you'll gain because you don't go to the gym anymore. Why don't you go there? Because you're addicted to your game projects, and all else has ceased to matter. You probably wouldn't eat if the roach coach didn’t come around with lunch every day.
Besides the weight gain, you'll likely develop carpal tunnel syndrome, making your hands and arms distorted like a zombie from a... video game. Your progressively worsening eye strain will make you see multiples of everything, which could pose a problem when you're designing virtual villains and heroes. Your eye doc will love your new career, as he's guaranteed to put his kids through college on your business alone.
We've saved the most sinister danger for last. Remember that movie about the guy who got sucked into his video game? Well, that film was based on an urban legend that was never really debunked. What danger does that pose to you, sitting in front of your computer screen? Let's just say your coworkers shouldn't be surprised to find nothing left of you but your coffee cup and some scribbled notes about a sinister video game plot. However, don't worry about being missed—someone has already claimed your cubicle.