Video Game / Plague Tree

Shown: Virus, Infectivity, Replicators, Uncoaters, Symptoms, Deaths.

Plague Tree is an Idle Game made in The Modding Tree by Vorona and released in 2020. The game's goal is to reach as many cases of the COVID-19 disease as possible (initially called the "Vorona Cirus"). As you go down layers, you unlock things that greatly improve virus spread and strength, way beyond what the real virus could possibly accomplish.

It is playable on galaxy.click and GitHub.

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This game provides examples of:

• Anti-Frustration Features: Making multiple attempts at mutating and showing formulas requires the player to hold the Shift key. For mobile players or those who don't want to/can't hold it, there's a Toggle Shift option in the info tab.
• Arson, Murder, and Jaywalking: Almost all upgrades in the Death layer have names that are synonyms for dying, like "Deadly", "Expire", and "Slaughter", but you also get "Blood Transmission" and "Dangerous"^note it implies death, but isn't really synonymous.
• Betting Mini-Game: In the Anti-Maskers tab, you unlock an Anti-Roulette that lets you win the respective resource if you correctly bet on red or black, later there's an option for green which provides better rewards. Soon you can get a multiplier based on win streaks. You gain 10% (increased later) of the amount you'd bet every second to make things fairer.
• Cap:
  • Casuals are limited at 1.8e308 for a while. You can reset them for Replicated Boosts once you have that many and the limit eventually breaks.
  • In the infecters layer, you discover cases are limited by immunity. Upgrades divide it to weaken the effect significantly, but sometimes it will limit production anyway. It eventually puts max cases gain at 1F10, but Anti-Capped pushes it further. The base cases gain does hit the library-enforced cap of F1.798e308 when you haven't even made 2% of progress through Booster Vaccine, but the other factors that affect it are significantly more important and it does not happen in the main game.
  • Also in the infecters layer, buyables are limited to 1,000,000 million levels. The Max Buyable buyable raises that cap.
  • Yet again in the infecters layer, challenges can only reach 1,000,000 points, and there's no way of raising that.
  • A bunch of infecter upgrades, as well as features like infection power, molecules, and MMNA are capped at 1F6, 1F7, or 1F8.
  • The level of the PrP Boost buyable can't go above 100.
• Challenge Run: You have challenges in several layers where the game puts a restriction and requires you to reach a cases goal for some kind of reward.
• Color-Coded for Your Convenience: Each layer and some tab groups in larger ones have specific colors to help with differentiation.
  • Virus: Gray
  • Infectivity: Dark red
  • Replicators: Pink
  • Uncoaters: Light blue
  • Symptoms: Somewhat light green
  • Deaths: Red
  • Fatality: Bright red
    • Casualty: Dark purple
  • Infecters: Aquamarine
    • RNA: Sea blue
    • mRNA: Green
  • CTNA: Dark sea green
    • Anti-Vaxxers and Adverse Effects: Purple
    • Vaccination and Adverse Vaccines: Dark navy blue
    • Anti-Boosters and Anti-Distancing: Light pink
  • Unvaxxed virus: Cadet blue
  • Unvaxxed infectivity: Dark pink
  • Unvaxxed replicators: Blue
  • Unvaxxed prions: Turquoise
  • Unvaxxed uncoaters: Lavender
  • Unvaxxed symptoms: Mustard
    • Mutated rRNA: Cobalt blue
  • Unvaxxed deaths: Magenta
• Completion Meter: The Booster Vaccine challenge shows its super-logarithmic completion percentage while active, as well as the percentage for unlocking UnBoosted Viruses that becomes a percentage to the next UnBoosted Virus or an order of magnitude of them later on. You can check the Unvaxxed Layers sublayer to see it on a bar.
• Cooldown:
  • Unvaxxed virus has a cooldown of 1.5 second between resets, unvaxxed infectivity has 5, while unvaxxed prions has 7. This is done to prevent spamming and give some time to purchase buyables.
  • UnRecover has a cooldown of 45 seconds between uses. UnBoosted Virus milestones make that increasingly shorter, until it's always active with the 2.5e14 MMNA milestone but can be triggered again to have its effects stack though that becomes unviable when unvaxxed tRNA increases so fast you're not able to click it again. A similar thing is done with UnRetRNA that initially has a 60-second cooldown, but it doesn't get an always-active milestone (however, it does get an auto-trigger milestone) and fall below 10.8 seconds.
  • The various automators unlocked in the UnBoosted Virus sidelayer all have cooldowns that can be shortened to as low as 0.1s with that resource.
• Crawl: There's a news ticker that shows various news related to the game or just jokes, but it eventually stop working.
• Diminishing Returns for Balance: There's a bunch of softcaps implemented to lower resource gains if the numbers start getting excessive.
  • Many buyables through the game eventually become "distant" after buying enough of them, which massively increases their cost scaling with every further purchase, and some of them can be bought enough to, fitting the theme of the game, become "social distant", which makes the cost scaling extra-large. Many upgrades and other effects are dedicated to pushing back the starting points for these indirect softcaps
  • After reaching 1.8e308 severity, recoveries start to gradually build up with severity gain getting divided based on the number of them. You start to power it down with certain challenges and get rid of it eventually.
  • After reaching 1e30,000 CTNA, the game puts a fractional power to its gain. The softcap starts later based on Coronas.
  • The 73 upgrade in Anti-Vaxxed Vaxxers has its effect softcapped once the reset time exceeds one hour.
  • After exceeding 1e308 Adverse Vaxxers, the game notes that their gain is softcapped. It eventually gets softcapped^3.
  • Unvaxxed infectivity gain is softcapped at 1e100.
  • Above 1.8e308 unvaxxed severity, you start producing boosted recoveries that make you lose a certain percentage of unvaxxed severity and even atoms later on each second.
  • Above 1e11,000,000 unvaxxed severity base gain, it becomes gets softcapped and has a fractional power applied to it. Another softcap is applied at e100,000,000,000 and another above e1e20.
• Double Unlock: Unvaxxed uncoaters introduce milestones which have additional effects that are unlocked only once the player accumulates enough uncoating power, alongside introducing upgrades that require achieving another condition before you can buy them with the main resource (in this case gathering enough PrPres before you can spend uncoaters).
• Export Save: You can export the 19KB+ save into a clipboard and paste it into the game.
• Factor Breakdown: Holding Shift in the tRNA tab shows the unvaxxed tRNA gain and the worth of each variable that's part of it.
• Fun with Acronyms: The first five layers: virus, infectivity, replicators, uncoaters, and symptoms, spell out the word "VIRUS". Also a Recursive Acronym.
• Gameplay and Story Segregation: You can see the "Vorona Cirus claims its first death" message long before you actually have even one death.
• Magikarp Power: When you first unlock the Coronas tab of CTNA, the third Corona Booster that boosts After log is so lacking that you're better off not buying it for the unspent Coronas multiplier, but not only do you eventually get an upgrade which makes the multiplier based on total instead of unspent, making buying the third boost somewhat viable, after a while the After exponent increases enough that the third booster gives the biggest benefit of the three.
• Mutually Exclusive Power Ups:
  • In the Infections tab, you can only have one path active from the three-way split. The Ininfection upgrade lets you pick two, while Infrection lets you pick all three.
  • Anti-Vaxxed Vaxxers have three instances where you can only pick one upgrade path. These are eventually removed with the Adverse Capper, AdAnti, and 999 upgrades.
• Not-Actually-Cosmetic Award: Every achievement gives achievement points that boost cases gain slightly and count towards milestones as well as some other gameplay buffs.
• Not Completely Useless: Unvaxxed symptom milestones 60 to 69 are just random facts about COVID-19 rather than boosts or convenient features. This seems useless at first glance, but the UB23 upgrade doubles UnBoosted Virus gain per US milestone after 59, making them actually helpful for gaining that resource.
• Number of the Beast: The CorVid City upgrade costs e6.66e666 CTNA.
• Only in Florida: Referenced in one of the news messages.
  Florida Man attempts to port Plague Tree to PICO-8, is stopped by the heat death of the device.
• The Plague: Since you use the COVID-19 virus and try to reach as many cases as possible (way more than real people on Earth), it's to be expected.
• Rainbow Speak:
  • The x variable in the Anti-Roulette is written in red, while the abc variables are blue. This carries over to some upgrades and buyables that reference them, with one writing "GREEN" in its respective color. Something similar is later done with unvaxxed tRNA's variables.
  • Once you unlock the various Anti-Vaccines, the note that states which type is produced by which AdVaccine is written in its respective color, unlike the rest which is black.
  • Resource names in Unvaxxed symptom buyables are written in a color related to them, albeit slightly darkened and shadowed.
• Random Drops: Mutations have a certain percent chance to actually succeed and increase the virus number when bought, which goes down with each successful mutation.
• Red Herring The 20th UnBoosted Virus milestone, which buy-maxes rRNA buyables and requires resetting in less than 3 seconds, also states that it lessens the "UnRetRNA" cooldown to 14 seconds. You'd naturally assume this means you would get it before milestone 21 which shortens that cooldown to 13 seconds, but not only will you get milestone 21 first, you'll be getting many more later milestones and several upgrades that continue lessening the cooldown long before you finally get milestone 20, meaning both the cooldown benefit and its placement in the milestone list is a lie in regards to when you'll achieve it..
• Remixed Level: Entering Booster Vaccine makes the game use two layer types that you can switch between at any time: Normal and Unvaxxed. The former are taken from the main game, while the latter are more complex versions of the normal ones with their own unvaxxed resources. That said, there are also some completely new layers like unvaxxed prions.
• Reset Milestones: Starting from Infectivity, each layer has several milestones that provide conveniences like keeping upgrades on reset or gaining 100% of a resource per second, with later ones also unlocking new features (this happens a lot since layers starting from Fatality get very complex) and boosts to production.
• Serial Escalation: Throughout the game, the virus becomes more powerful in increasingly complex/devastating ways. The very early game is about improving the virus's infectivity and replication. The early game focuses on symptoms and deaths caused by the virus. The midgame is about infectivity again, but this time in a way that's more about reducing the immunity that has built up and dealing with a quarantine. The late midgame is about RNA and various other genetic concepts like Atoms, Molecules, mRNA, MMNA, CRNA, and CTNA. The late game is once again about increasing how infective the virus is, but this time by accumulating things to get past a vaccine. Each layer also gets longer past a certain point (the earliest six only have a few tabs at most, Fatality has ten, Infecters have eight with seven subtabs in the last one, while CTNA has several sub-subtabs and a long Booster Vaccine challenge with its own set of layers).
• Shout-Out: Most of the Fatality layer references Antimatter Dimensions. There are Fatality Dimensions where the higher ones produce the one below its layer, Fatality Dimension Boosts work similar to Dimension Boosts, a Sacrifice feature multiplies the power of Dimension 8, and Casualty has a slew of references to Infinity (similar upgrades for Dimension pairs, a multiplier for itself, challenges for Fatality and Casualty, autobuyers, its own set of Dimensions that are unlocked once you reach enough Casualty, and Casuals that function similarly to Replicanti). Most of the achievement names related to the layer also reference AD in some way.
• Skill Point Reset: You can reset infections, which is often necessary if you need different paths or need to build up infectious diseases since they get multiplied by those you haven't spent. Coronas can also be reset, but that's only needed at the beginning if you need to gain CorVids. A similar thing is done much later with Anti-Vaxxed Vaxxers, though there it's only done to select a different path.
• Spoonerism: The game revolves around the "Vorona Cirus", rather than the coronavirus, according to the tab name and news.
• Theme Naming: The very short names of the upgrades in the Anti-Boosters tab spell out "Anti Booster Adverse Vaxxer Vorona Infect Diseases".
• Villain Protagonist: You, for controlling the world's deadliest supervirus.
• Year Inside, Hour Outside: Anti-distance multiplies the time at which the game runs. Several achievements require a reset time that would be exorbitant in reality (like 2023 years), but is totally achievable because of game-time.

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