Alien Host

6th March 2005

Single Player First Person Shooter Maps and Mods for Half-Life 1, 2 and Episodes 1, 2 and 3

Here is another alien invasion idea similar to the Trust Mod Idea. However this story has a more detailed background that I have taken care to ensure is as realistic as possible. Too often in these types of stories the actions that either lead up to or happen just after the invasion are beyond belief. I keep saying to myself “there’s no way they would do that!”. As I’ve said, in this story I’ve tried to make the action believable. Whether I’ve done that or not only you can decide.

For me, the enjoyment is in considering the finer details of the story and elements within it. Whilst it is not necessary to read the background information I believe the reader will gain more by understanding the whole situation rather than your part (as the main character in the mod) in it.
The story is part of the Half-Life 2 universe and happens just after the Combine invasion, although the events that lead up to the beginning of the mod have taken place a LONG time before. The background is quite long, so get comfortable.


The idea revolves around the concept that an alien civilisation has managed to send an intelligence through space via radio-type signals into a military network. The aliens want to infect electrical systems (knowing that this is probably a universal way of using energy) and take control of a planet. This is not specifically aimed at humans, just any intelligences that happen to receive the signals. For them this is a tried and tested method because after thousands of years of trying, this particular alien race could not find a practical way of travelling between the stars. However by sending out information in every direction they are able to ensure their continued survival.
Of course, the problems of very different electrical systems require a very highly developed intelligence and these aliens are exactly that. They are also very patient and careful, they may only get one chance to infect a planet or installation, so they ensure that they don’t waste it.
The question is, once the alien intelligence has been received, how does the alien move from electrical system to controlling the planet? Well, it often tries to transfer itself to an animal host. A means needs to been found for the alien to force a human to make prolonged physical contact with the electrical system. In this case, it has found that humans are desperate for alien contact and has created a Fictional Alien Race (FAR) of beings that have pretended to have received very earlier radio signals from Earth.

This FAR has seen the early TV shows and supposedly wants to make friendly contact with earth. The alien has simulated a signal from space with detailed plans of a device that allows humans to communicate with a virtual representative (VR) of this FAR. The machine is like a chair with a number of electrical contact points distributed around the body. The chair is connected to a computer that supposedly has the virtual representative from the FAR.
Of course the Generals in charge of the project are highly doubtful of the authenticity of the signals and situation. Many believe it to be the work of a foreign power or worst an aggressive alien race. There are many questions left unanswered. Why do they need to build a machine to communicate with the VR? Why can’t they just use the computer? How come the aliens know so much about the physiology of humans from simple TV shows? Clearly this project needs careful consideration and management.

A lot of these types of questions were anticipated by the alien who tried to include as many answers as possible in the simulated signal. But these humans are a distrusting bunch but their curiosity will get the better of them and eventually they will build the machine. After approximately 5 years of discussions on the possible negative effects, the machine is built and as many precautions as possible are put into place. A special base is built deep underground with only one entrance. The base is completely surrounded by a variety of layers each one designed to protect the base in one way or another. For example, there is a layer of inert liquid that prohibits the transfer of electrical signals, another layer contains radioactive waste. In total there are 12 different layers and this base is without doubt the most sophisticated and secure facility every created by Man.

A volunteer is selected and placed in the machine. The “operation” seems incredibly successful and the subject is able to answer questions as if he were representing the alien race. He say the process is fully reversible and the human subject will remain completely unharmed. The subject gives snippets of advanced information concerning technology. It pretends to want to avoid anything concerning weapons technology and expresses its delight in being the first alien race to contact humans.

The subject is kept within a sealed area and the military plan to kill the subject on completion of the experiment. The subject gets very tired due to the increased brain wave activity and requires over 20 hours sleep a day. This means that communication is slow. Of course, the alien inside the subject is plotting its escape and assumes that it will never be in contact with humans directly and also knows that the subject will be killed at the end of the experiment. It has left a copy of itself within the electrical system of the base as an emergency precaution. After a year or so the alien gets the feeling his host’s time has come and suggests that the procedure is reversed and request that a data log of his communication is sent back to his home planet and for the humans to await a second response that may bring more technology as a sign of friendship. This is of course false and the alien is just waiting for the right moment. As mentioned earlier it is very patient and is prepared to wait many decades for the right moment.

The procedure is reversed and the subject observed for another 6 months before being firstly gassed and then incinerated and the ashes kept sealed in a nuclear safe container. The Generals don’t want to take any unnecessary risks. No Star Trek style blunders here, thank you very much!

The alien continues its wait and its research about humans and the solar system it inhabits. By the time it is ready to simulate the second signal from the FAR, the Black Mesa incident has occurred and the Combine have invaded Earth. For the first time in its existence it is hesitant. The potential for profit here has increased a hundred fold; whilst the Combine isn't as technologically advanced as its race they do have Advanced Portal technology, something even these stupid humans had almost developed. It is amazed at how different alien races develop different technologies based on their circumstances. Its race has never considered portals technology seriously finding their power requirements too prohibitive, yet somehow those problems have been solved!

Eventually the alien decides he has to make a move now before the Combine find the secret base and begin a detailed examination of the data and find him. It’s not certain they have the ability but why take a chance? He simulates the second signal and the whole process starts again. This time the humans are desperate for help and give him information regarding the Combine and portal technology. They hope that the FAR could perhaps come to their rescue?

It pretends to be hesitant, they (the FAR) don’t want to become involved in a war BUT they have extended the “Tentacle of Friendship” (His little joke, worth seeing their faces when he said it!) and feel a certain responsibility. It requests actual physical contact with humans but is denied. The same procedure used last time MUST remain in place. It takes this with false good grace and reverts to plan B. After a month or so the alien has slightly changed the human’s host physiology to his needs. At a crucial time in the discussions regarding weapon production the host becomes very ill.

Medics are sent into the sealed rooms with protective clothing. The alien has changed the rate of growth the human host’s fingernails and scrumptiously made them sharper, almost like claws. As the medics enter he waits until they are assisting him and pretends to cry out in agony and grab hold of a medic. His nails rip through the clothing and create enough space in the protective clothing for the two humans to have skin contact.

Whilst the other medics restrain the host, the alien has passed enough of himself into the medic to be able have basic control over him. (We’ll call it the Alien Lite (AL). Not a complete intelligence, there wasn’t enough time, but enough to know that the host MUST be freed.) This medic is placed in isolation but has no symptoms and before he can be killed he has managed to touch other humans. This process continues until the AL has touched a guard with the ability to open the sealed isolation doors. This he does and then the alien completely transfers himself from the host to the guard, and then closes the door to look as if nothing has happened. It’s free. Almost!

Unbeknown to the alien, the facility has been under separate observation from the very beginning. The system is not linked in any way, shape or form with those of the facility. They do not share power or any other form a cable. The Alien had no idea of the second system. The Combine took over this observation as soon as they arrived. One of the first things the Combine do after invading a planet is to search for these types of bases, they often contain the real reason for the invasion. They were quite happy to continue the observation and see what happens. A lot can be learnt by watching aliens in action. They now know that the alien is free and the situation must be contained. Consequently they have sent a squad in to capture it.

Onto the mod!

You play an undercover guard, a bit like Barney, whose job was to keep an eye on things. Your commanders have intercepted the Combine’s observations and the Order to capture the alien. Your orders are simple. Stop the Combine from capturing the alien and if possible capture it yourself. Sounds easy! The plan is to try and negotiate with the alien offering it the ability to continue with its infiltration of the Combine in return for Earth’s freedom. Of course your Commanders aren’t naive and plan to kill the alien immediately after the Combine have been defeated. They give the mission a one-in-a-million chance of success. But in times of war every avenue must be explored!
In the meantime the alien has infected EVERYBODY within the secret base with the Alien Lite version. This means that to transfer from one host to another takes approximately one minute. The base’s staff do not know about the AL version and remember nothing from when they are infected with the full alien.


I’m hoping that the uncertainty of knowing who is the alien may make the game part psychological thriller, part frag fest. The Combine have entered the base and half your time is spent killing them and the other half is spent trying to find who is hosting the alien. You have a special weapon, details to be decided, that enable you to capture the alien. The weapon would be something like a net or other restrictive device. Your Commanders are concerned that a drug or stun gun may effect the alien inside the host and don’t want to take any chances of either killing or injuring it. This weapon is a use-once only type of weapon. No second chances. Careful observations must be made before using it. You have to watch how the other soldiers fight against the Combine, would this show you anything? Who knows? Would the alien try to infect a Combine soldier by getting close to them? Again who knows?

Once you have made you choice, and don’t take too long or the alien may be killed or captured by the Combine, you have to leave him/her where you have secured him/her and finish off the rest of the Combine to ensure easier extraction by your Commanders. As you search for the rest of the Combine you find that they are all dead, along with the rest of the human staff. SHIT! Was there another power at play here? On returning to the alien you find it gone! (A little predictable but what did you expect leaving it on its own?)

The gameplay changes to almost a survival horror. Find the alien without being captured yourself. This could turn into a BOSS type situation where the alien is very hard to wound (remember you have already used you capture device!) or simply a stealth situation.

The Ending

I have to admit that I’m a little vague of this part because I don’t want it to be too much like a Hollywood movie. The goodie kills the baddie and gets the girl and the money!! My thought process went something like this:

  • It’s highly unlikely that the Combine would send a few troops into the base and leave them to it. They would have

    re-enforcements waiting outside, with transport for the alien etc.

  • In that case your Commanders have very little chance of defeating the re-enforcements and entering the base.
  • When confronted with the re-enforcement Combine soldiers what would you do?
    • Kill the alien host?
    • Kill the alien host and yourself? Would you want to be tortured by the Combine?
    • Try and destroy the base because it contains all the data?
    • Look for an emergency exit? It may exist, although there has been no mention of it before!
    • Try and fight your way out! Yeah, like that’s gonna work!!
The Mod Mechanics

Without going into the level design in too much depth, I think this mod would require quite a lot of scripting to ensure things happen the way they should. I know players like to have choices etc but sometimes a story requires a limited set of actions. For example there could be quite a few occasions where as you are entering a room you see two soldiers touching each other, clearly the alien is transferring itself from one host to another. Before you can reach them they split up and run in different directions. Who do you chase? Without careful planning this would become very frustrating and ultimately boring. You might as well kill everybody in the base and at least you are sure the alien hasn’t escaped!

The Twist

I’d like to think that the game could end in different ways depending on your actions. For example if you did decide to kill everybody in the base then as the game ends, probably by you being captured by the Combine, then there is a voice that says something like “Thank You for allowing me to escape, at least I have a chance now of infecting both the rest of Humanity and the Combine!”.

Personally I would like the player to choose to destruct the base because it would provide what I would consider a realistic ending and also tie up any lose ends. Perhaps you have forgotten that the alien left a copy of itself in the electrical system? It’s unlikely the humans know this but why take any chances? The destruction of the base would deal with this issue or if the player, along with the alien, are captured, then the final shot of the game can be the Combine sealing the base but the system turning themselves on again as the copy alien continues to exist within the base.
Perfect for a part two?


  1. Daniel Bizzarri

    OMG nice post man, you put a LOT of thaught into that story, and I read every last bit of it, nice job, sounds realy awsome 😀 but you know wat would be cool, if you could BE the alien or the combine trying to get the alien and when you are successfull the alien infects the combine and the humans and sends a full attack on boath races…but its realy an awsome story nice job

  2. Thanks for your kind comments. I suppose you could play as the Alien, in fact I published an idea that may link perfectly, it’s called Transfer Your Consciousness.

  3. Daniel Bizzarri

    thanks for that and the reply

  4. No One

    Try being the one!

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