Around 2002 me and my brother experienced one of the strangest and weirdest phenomena together as we witnessed a ghost in the most bizarre way.
One Weekend he was playing the videogame Resident Evil (The remake version) on the gamecube and this game was a horror game with zombies, he got lost and didn't know where to go, walking around aimlessly on the corridors in the game.
In the videogame there is a L shape corridor with a mirror, staircase and a birdcage. In the corridor there's a corpse of a man in the corner that seems to have fallen dead without any signs of trauma. Now this corpse never moves or comes to life, it does however disappear later on in the game without any traces. So me, my brother and many others believed it to be programmed into the game.
Me and my brother joked and said how scary it be if when you turned the corner you see the reflection of the dead man standing and he comes to attack you, I was on the bed reading a magazine as he casually played it. I looked up from time to time to see his game character in the birdcage corridor, suddenly as he walked to the corner a shadowy figure came out and reached his arms and instantly vanished in a blink of an eye without any sound. During that brief time, my brother reacted by freaking out then quickly noticed it was gone.
Thinking maybe it was his imagination, he turned around to look at me without saying a word but the expression on his face was like "Was that just me, did you just see that?" I looked at him instantly and said, "I saw it!"
We were both perplexed, how did such a ghostly thing get into the game? This is mainly a zombie monster game, there are no ghosts in it. To this day we've been trying to find out what it was, my brother found out there was an enemy/monster code in the room but we've never met anyone who has experienced this phenomena. We can't explain it, if it was a glitch or if it was intentionally and secretly programmed into the game. All we know is that me and my brother literally seen a ghost in a videogame and have never seen or experienced it since.