Game World? I Invite You All to Die!

I am a time traveler. I originally thought that I was doomed to be lonely no matter in my previous life or in this life. But when I looked at my sister in this life and realized that the death of my parents was not an accident but a game played by others, I think I should know my mission. This is a world of hidden dangers, because you don't know what kind of terrifying existence will appear in the darkness next second. And with the help of the system, my variable will become their nightmare!