Non-Deadly Objects/Concepts that are Deadly in Video Games

You ever noticed that tons of things that really wouldn't kill you in real life, kill you in video games? Well, sadly, it's true. There's always gotta be something that gives you a game over, and game developers seem to grasp at straws to find something good to do just that. Here's a list of some of the most ridiculous things that kill you or others in video games. 
Any additions by the community are appreciated, I'm having a bit of a hard time thinking of good ones.

List items


To add:

- being seen (steatlh mission)

- flan enemies (cuz fuck that!)