This is a story primarily designed for Gordon Freeman in Half-life, but it could work with any well-known game character. The premise is fairly simple; After you have destroyed the Nihilanth and you face the Gman who gives you that fateful choice, as you walk into the portal there is some kind of error and you are transported back to Black Mesa.
You seem to have gone back in time because you arrive a couple of minutes after you pushed the cart into the beam. BUT, this Black Mesa is different. You are in a Reflective Dimension. Here, everything is reversed. Character traits, colours, sound etc. Your Doppelganger, is not quite as nice and helpful as you are and has decided to run amok and kill as many people as possible. The aliens seem to have taken a liking to him and are helping him in any way.
Catch him as quickly as possible and kill him, worry about getting back to your dimension later.
Those regular readers will know that I try to link the gameplay with the story in some way shape or form. The Reflective Dimension reverses as many environmental characteristics as possible (see later) and this could translate into a reversal of game playing styles. Obviously you don’t really get to fight against the Doppelganger until very near the end of the game. Whatever playing style you have used up to this point will be reversed and used as the playing style of the Doppelganger. For example, you play cautiously and carefully, never rushing into situation and taking time to consider options when possible. When you finally play against the Doppelganger he plays recklessly, rushing in and using firepower to win.
The game doesn’t have to use all the same maps used in Black Mesa but a good proportion should be used. However they will be reversed in the vertical plane, meaning left becomes right and vice versa. I also feel that colours and should be changed. I don’t know if there is such a thing as an opposite colour but as long as scheme is stuck to then that should work. The sounds may prove a little harder, perhaps they could be manipulated in a synthesizer to either a higher or lower frequency. It may be fun to hear the voices changed.
This is of course the climax of the game and should take place in a number of different locations within Black Mesa. It should be clear from early on that he is running scared and wants to avoid you. It should also be clear that every time you hit him not only does his health drop but so does yours! A little careful coding will ensure that yours finishes before his. It’s also worth noting that the final battle is played out with only the Glock 9mm Pistol. Each hit is worth one health point.
Throughout the game you overhear scientists talking about dimension and matter etc. The only way to kill him is to occupy the same space at the same time. This means running into him. The game ends when you finally manage to corner him and run straight at him. The screen fades to black and you hear some scientist talking.
Scientist One: “Amazing, a trans-dimensional dual occupancy phenomena.”
Scientist Two: “Yes, but did you notice the slight shift in the super string spectrum?”
Scientist One: “No, are you suggesting that instead of mutual destruction they have simply randomly jumped into other dimensions?”
Scientist Two: “Yes, but the interesting thing is…..”