Heavy Weapons runs on the basic premise of a multiverse. A infinite series of parallel universes that run on forever, each completely separate from its brothers and sisters, never to touch or interact. With that in mind:
A normal, healthy universe like our own shouldn't have any anomalies occur at all. There are rules, physics and physical laws that underpin every interaction within that universe, they are what make anything possible. Without the laws of chemical interactions and nuclear bonds for example, no physical matter would be possible, these laws of physics are written into reality itself, known as the space-time fabric. It is a meta-physical manifestation of the reality and its laws for existing within it, if you don't follow the rules, you can't exist. That's a lot of big words to describe the world as we see it, but its important to note that this fabric of reality can be distorted, damaged and even completely destroyed, the effects of which are not always immediately apparent.
As previously mentioned, when the fabric of reality is undamaged, like our own universes, everything functions as it should, but when this is distorted, it can give way to anomalies. These are unexplainable, impossible events that can only occur when this fabric is distorted, the deeper the distortion, the higher the chance of larger and more dangerous anomalies.
Anomaly generation is inversely proportional to the overall health and status of a universes reality, I.E. The more anomalies generated, the more unstable and dangerous the universe is. A lot of realities aren't in danger if the damage to their fabric is low or moderate, although the low to moderate anomalies are certainly strange, they don't pose a threat to that realities existence as a whole, but there is a thresh-hold that will all but guarantee the early death of an entire reality should it be crossed. Once a universe starts generating anomalous materials, its days are numbered. The existence of these materials is a sign that the fabric of reality is greatly damaged and their generation will speed the death of that reality up significantly.
There is only one universe within the infinite parallels that has managed to prevent its own death by anomaly apocalypse and that is the one my fiction focuses on, but the rules of anomaly generation and their consequences are consistent through-out all realities.
But as previously mentioned, the existence of low to moderate level anomalies is something that most realities can cope with. These unexplainable events vary greatly in their effects and are categorised as per their danger to living creatures.
Threat 1 - “Unnoticeable” level events
These are generally very small changes to molecular arrangements, small electron manifestations, tiny unexplainable events that only sensitive equipment can detect, nothing to be concerned about but a sign of instability in the fabric. These are often to blame when someone enters a room and forgets what they entered for as they can interrupt the neural pathways in your brain just enough to stop a thought.
Threat 2 - “Low” level events
Low level events are usually mildly interesting to witness and mildly annoying at worst, the sudden drop of temperature in a room, a gust of wind when all the windows are closed and properly sealed, the disappearance of your favourite pair of socks, they don't tend to effect living creatures, but they provide greater evidence of reality distortion. Other examples include spontaneous minor internal damage to inanimate objects (Such as a light bulb suddenly popping) and extremely mild energy generation, like a dull burst of light or random radio-wave signals generating from nothing.
Threat 3 - “Mild” level events
The last tier before fabric disruption becomes severe enough to threaten existence. The consistent generation of anomalies in this tier is strong evidence that there has been significant damage to the threads of the universe as its rule-set is permitting more errors than it should. These are more powerful than the previous tier and can effect living creatures, including spontaneous teleportation, stronger energy spikes (or energy destruction), sudden and violent damage to materials and the generation of non-anomalous physical matter, such as gas or metal. They can also change the properties of existing materials in potentially good or bad ways, but nothing that would break the laws of physics too severely. For example, an anomaly could harden a length of steel beyond its normal strength by ten fold, but it couldn't make it generate energy for free.
Threat 4 - “Strong” level events
These anomalies can pose a vast threat to living creatures and is the first tier that can straight-up kill if caught in. If a reality is producing anomalies of this severity, its only a matter of time before an anomaly apocalypse happens. These are similar to the previous tier in effects but larger in strength, a “strong” level energy discharge would be more than enough to kill someone caught in it, for example. Material modification anomalies can now amend existing materials with significant, impossible properties, allowing for the creation of “magical” artefacts should the metaphorical dice be rolled well.
Threat 5 - “Severe” level events
These are upscaled again compared to strong, but now also include the generation of anomalous materials, with impossible properties. The mere fact that these materials now exist within the example reality is evidence that its rule-set and laws are failing. That doesn't mean that everyone in that reality will die instantly, but if “Severe” level anomalies occur, for all but one universe, it means the end is coming, they will cascade out of control eventually.
Threat 6 - “Cataclysmic” level events
These only happen when a universe is on its deathbed, its reality unravelling at the very seams, entire planets and solar systems vanish from existence, anomalous materials are generated in massive amounts, energy and matter flicker in and out of existence as reality itself glitches and strains to stay together. Any universe that suffers these is likely only months from ceasing to exist at all.
When a universes reality is damaged and it begins to produce anomalies, there is a tolerance for these events up to a certain degree, imagine it like surface damage to a person, uncomfortable but survivable. But much like a person, if the damage is too severe, it causes knock-on effects that'll lead to death. Like a stab in the guts, higher level anomalies cause a bleed out effect, where unless addressed, they'll end up destroying everything. This is done almost entirely by the anomalous materials generated in threat 5 “Severe” level events. The existence of these materials causes distortion in the space-time fabric, if the fabric is already damaged enough to cause these materials to spontaneously generate, then they'll self accelerate their own random creation by distorting the fabric further. These Anom-materials can also cause tremendous physical damage that'll destroy everything by itself when given enough time. Novarium comets are particularly dangerous as it will heat itself up infinitely, eventually being trillions of degrees hot and bathing everything within its sphere of influence in vaporising plasma, just one of these flying through the cosmos would be dangerous enough, now imagine what would happen if they were randomly popping into existence all over the place.
Once a reality begins generating anomalous materials, it cannot stop, spiralling out of control as the laws of physics bend and break further. Eventually, that reality will break under the weight of its out of control anomalous materials, completely shattering out of existence and disappearing for good, its final weeks spent bathed in impossibly hot Novarium fireballs or reduced to nothing but Severmeld as every atom within is converted. There will be nothing living at this point within that universe, it will be a completely chaotic, impossible mess of anomalies, its planets and stars irrevocably decimated and scrubbed from existence by the raging hell-scape that barely fits within its engine. This is an anomaly apocalypse, a reality that has been damaged beyond repair, its rules discarded and the result is complete and utter chaos.
What damages the fabric of reality?
Thankfully, most universes do not meet this fate, most will never have anything beyond a threat 1 “Unnoticeable” event and beyond that, its also incredibly difficult to damage the fabric of reality, as its an omni-present meta-construct, its easily able to handle anything within its own rule-set. You could set off a billion nukes at a single point and only cause a brief distortion in the fabric temporarily, this is why most universes will never experience any particular surge in anomalous activity. You cannot overwhelm the engine of the universe with sheer numbers for the most part, the biggest reason for anomalies are living organisms themselves. Of course, 99.9999% of all living creatures will never distort or damage the fabric and even those who do, will only damage it locally, usually to an extent that is tolerable as previously mentioned. There are two main causes of anomaly apocalypse, the first is someone within that universe damages the fabric enough to cause threat 5 “Severe” level events to occur, causing the formation of anomalous materials, it may take millions of years but given the life-span of universes, this will still cut their lives down significantly, the creature that caused the damage would have likely perished of old age long before it even knew what it did. For those wondering, its usually extremely dangerous and far reaching scientific experiments that cause reality distortion, anything that pushes the limits of physics (I can't give examples obviously, i'd be putting everyone at risk). The second main cause is by extra-dimensional invasion by “The Legion”, which causes catastrophic damage across the entire universes fabric and will lead to its death in a few short years.
The universe we focus on isn't the only unique universe within all of meta-existence. There is another that has caused untold death and damage. Within one universe, a faction managed to gain technology to allow them to breach between universes, how they accomplished this is a complete mystery as the rules within universes simply do not allow for any form of dimensional hopping between parallel universes, it should be completely impossible but it allows them to tunnel into parallel universes and launch exo-universal invasions, they attack to take matter and energy back to their own existence to further fuel their war efforts, plus any technology or species that might benefit them and depart, leaving the invaded universe in complete disarray. The damage caused by these exo-assaults is ruinous beyond measure, essentially opening up millions of threat 6 “cataclysmic” level events as extra-dimensional wormholes across all of space, allowing The Legion to cross the barrier and invade. Beyond the physical devastation, the fabric of reality is severely damaged in an uncountable number of places by the forcible intrusion and any universe that is subjected to this assault inevitably ends up falling into an anomaly apocalypse within days of being attacked.