Basic Idea
The government funded research facility Black Mesa has currently been undergoing a project to try to create a wormhole and effectively reach another world, or create a way in which one might reach another world. In what first appeared to be a failed experiment, though which now is considered to be a success, though very disastrous (like an atom bomb going off and blowing everything up, it worked but now everyone is dead mmhmm) caused a link to be made with another world causing beings from another planet, dimension, or from some area to come into the Black Mesa research facility. The survivors from the initial explosion, who's percentage is very small compared to the original couple thousand people working there, are now slowly being dwindled away by aliens, the place falling apart, and marines alike. U.S. marine soldiers, given the order that they must kill everything within the area, do not take into the account that some people may or not be humans. As head crabs are now capable of killing and taking over the central nervous system of human beings and other creatures, there are now essentially head-crab "zombies" which are dead people being controlled by head crabs. There is also mutagenic toxic waste lying around which is altering the DNA of the very versatile yet lethal zombie like alien type creatures which consists of head crabs and other aliens. In short, their are four groups : Survivors, Marines, Aliens, and Aliens and zombies. Unknown to the humans, the head crab zombies and the humanoid aliens are to disagreeing races being brought to our world, unknown to the aliens the U.S. marines and the survivors are two separate waring groups and the and unknown to the survivors the marines are trying to kill them. This leads to a very hostile environment where a military government funded research base is now under lock-down from the U.S. marines and aliens, zombies, soldiers, and survivors of the big explosions and aliens are now all fighting to kill each other. Survival rate is very low. The object is to get outside to the outside world, alive, and then make it out of the Black Mesa Facility.
Groups
Head Crab Zombies/ other aliens-
(Non-Playable)
The head crabs are very versatile but basic creatures who simply roam around, feed, and eat other creatures for their basic nutrition. Also containing the ability to take over the nervous system of whatever creature they encounter, they are capable of killing or taking over dead bodies by attaching themselves to the central nervous center of the creature and then injecting a nervous system deterrent, slowly paralyzing the victim and then taking them over. The head crab then spends several hours, if not days, connecting capillaries of the head crabs body with that of it's victims, creating veins and eventually making it so whatever the host consumes the head crab can absorb through the creatures own vascular system, and utilizing the hosts digestion system can get nutrients. In sense, the head crab is a parasite, however they can live just fine by feeding off of anything around them and possess a small and rather weak digestive system that is capable of digesting small things. The head crab uses it's own sensory organs and does not require those of it's hosts, however does still feel what the host feels as the two nervous systems are connected, and can actually be killed by killing the host (if the head crab cannot detach in time or detach at all.) The head crab however does use the hosts vascular system, muscular system, respiratory system, nervous system, and digestion system, and only occasionally it's excretion system, and many other things. The head crab itself is very easy to kill though their modified hosts may not be. The other aliens in these systems are primarily dog race creatures with only hind legs, and though do not pose an alliance with any headcrabs, are not a part of any alliance of aliens at all and so fall into this class. Mutated aliens also fall into this class as primal non intelligent creatures, they are essentially the deer, dogs, cats, and other creatures of their planet compared to humans, though when compared to humans are hard to tell apart from which is which if an alien creature were looking at them.
Aliens
(Playable)
]The intelligent aliens, or Xen, have been accidentally teleported to Black Mesa as well with the head crab aliens that they were at war with, and with many of these creatures around the Xen are simply trying to kill anything which comes there direction. Very intelligent, and capable of using or modifying human technology, they Xen are simply trying to escape, and in secret, build a system with the humans own technology to try to teleport themselves back to the home world or find a way to teleport more here or get back to their home planet.
U.S. marines
(Playable)
Given direct orders to go and kill everything in Black Mesa compound, they are currently at war with the alien and survivor groups who are trying to exit or leave the area. They are given the order to not let anything leave the premises, and if anything tries, to kill it. They are also responsible for killing everything inside while maybe finding some survivors. They are not allowed to explode the entire compound for fear of killing someone important and also for fear that whatever is in there might react to it, as well as to keep it a covert operation that no-one finds out about.
Survivors
(Playable)
Survivors of the initial explosion, the survivors now face aliens, zombies, parasites, marines, and the harmful chemicals and areas of the main facility while desperately trying to escape the facility and get far away. The groups of the survivors mainly consisting of guards and scientists, they are poorly equipped for dealing with both threats, though with their ingenuity will acquire the abilities and means to escape from the facility. They can start with crowbars or small pistols depending on their job descriptions. Some may also have knives or improvised materials as weapons.
