Steins;Gate has chosen you! You now have the power to predict the future! Nah I'm kidding! It's just that you probably have a very good imagination, and that it happen to be a coincidence when you played the game. I honestly don't know what else it could be. Same thing happened to me with GTA V, before the character switching mechanics were announced, I dreamed of switching to Michael who was driving his Tailgater in the desert, then I switched to Trevor who jumping off of Mount Chiliad covered in snow, and there was water below with icebergs and sh*t, none of that happened in the actual game but the snow cheat is possible though.