The thing about being a heterotroph was that the world suddenly had texture.

  Before the evolution, Andy's perception of the pond had been a chemical smear: "food over there" and "not food over there" and, occasionally, the more urgent "something large over there, move." Navigating a city by smell alone, except the city was an ocean and he was a grain of sand.

  After the evolution, the smear sharpened.

  [Active Hunting] had upgraded his senses from "blunt instrument" to "something almost precise." He could differentiate between types of organic compounds now: sugars here, proteins there, lipids in a cluster to what his internal orientation insisted was "north." More importantly, he could detect other living cells, their metabolic exhaust trailing behind them like footprints in snow.

  He could track things.

  Andrew Snodgrass, veterinary technician, animal lover, the kind of man who carried beetles out of his apartment in cupped hands, could now hunt living organisms with directed, intentional, predatory focus for the express purpose of stabbing them with his horn and eating whatever came out.

  The cognitive dissonance was manageable because the things he was hunting did not possess consciousness or the ability to suffer. They were cells. Biological machinery on chemical autopilot, no more aware of their existence than a thermostat was aware of temperature. He was eating thermostats. Thermostats with cell membranes.

  This was fine.

  "And here," Andy narrated to absolutely no one, in the private theater of his own mind, "we observe the heterotrophic prokaryote in its natural habitat, fresh from evolution and positively bristling with new abilities. Note the enhanced chemoreception, the pseudopod extensions, the general air of menace that it wears like a very small, very pointy hat."

  David Attenborough, or the memory of David Attenborough filtered through the neural patterns of a dead veterinary technician now piloting a microscopic predator, provided the narration with a gravitas that the subject matter absolutely did not warrant.

  "The predator has identified a cluster of unsuspecting prokaryotes gathered near a thermal gradient. They are fat. They are slow. They have made the critical evolutionary error of not developing a horn, which, as we have established, is the single most important thing any organism in this pond can grow."

  He paused. Even in his own head, that one had layers.

  He extended a pseudopod, the new ability manifesting as a temporary bulge of cytoplasm he could push outward like an arm made of jelly, and used it to stabilize his approach. The pseudopod was weird. Not unpleasant, just weird, like discovering he could wiggle a muscle he hadn't known existed. He could anchor himself, change direction, or grab onto things, all of which made him a significantly more effective predator than the free-floating blob he'd been before.

  Or twelve days ago. Time. Still unclear. Moving on.

  He crept (drifted with hostile intent) toward the cluster of cells, horn-first, pseudopod braced against a grain of sediment, and picked his target: the largest of the group, a plump cell radiating the chemical equivalent of "I have recently eaten very well and am too full to move quickly."

  "The horny prokaryote," he narrated, because the pun sustained him even without an audience, "stalks its prey. Note the horn, extended at the leading edge of the cellular body. One-tenth the length of its total body. In human terms, this would be equivalent to a man carrying a sword roughly the length of his forearm. In prokaryotic terms, it is devastating. In phallic terms, it is... well. Moving on."

  He struck.

  Pop.

  That sound. That perfect, satisfying little pop of membrane giving way. He'd felt it during his first kill and it hadn't gotten old. The cell burst open, its contents rushing out in a warm gush of proteins and nutrients that his enhanced absorption processed with fifty percent greater efficiency than before. More nutrients per kill. Faster energy. More hunting. More XP. Andy was becoming a perpetual motion machine of consumption and violence, a feedback loop that would have horrified his human self and delighted his gamer self. At this point, those were the same person.

  [ORGANISM DEFEATED: PROKARYOTE (NUTRIENT-RICH)]

  [XP GAINED: +4]

  Four XP. One more than the standard kill reward. The nutrient-rich tag must have contributed a bonus, which meant that targets varied in value, which meant that Andy needed to start categorizing his prey by XP yield, which meant he was, god help him, developing a loot table for pond organisms.

  He moved to the next target. Pop. Then the next. Pop. Each kill was faster than the last, not because the targets were getting easier but because Andy was getting better at the sequence: approach, stabilize, thrust, absorb, move on. He was developing technique. He was developing style.

  He named the moves.

  This was perhaps the most telling sign that Andrew Snodgrass remained fundamentally, incurably, a nerd. He named his combat techniques the way a kid names backyard attacks, except the backyard was a pond and the stick was a horn and the imaginary enemies were real organisms that went splorch when punctured.

  The basic frontal thrust, horn leading, maximum velocity, was "The Snodgrass Special." (He was aware of how that sounded. He did not care.) The angled approach, coming at a target from above to pierce the thinner dorsal membrane, was "Death From A Vaguely Upward Direction." The pseudopod-anchor-and-pivot, where he braced against a surface and drove the horn in with extra force, was "The Fulcrum," which was the only one with a name that sounded even remotely cool, and he was proportionally proud of it. The surprise attack from behind was "The Proctologist," which he immediately renamed "The Ambush" because even alone in a pond, a man has limits.

  [XP: 23/100]

  He hunted. He ate. He grew.

  * * *

  The pond, Andy was learning, was not a static environment.

  He had assumed that the warm water would stay warm, that the nutrients would keep flowing, that the chemical gradients would continue pointing him toward food like a GPS recalculating after a wrong turn. He had assumed, essentially, that the tutorial zone would stay tutorial-zone-shaped until he was ready for the next area.

  This tale has been unlawfully lifted without the author's consent. Report any appearances on Amazon.

  The pond did not agree.

  The temperature shift started as a subtle cooling at the edges of his awareness, the way a room grows darker before someone notices and turns on a light. The warm water began to cool from the surface downward, and with the cooling came consequences.

  Everything slowed. Active predators became sluggish. Sluggish cells became inert. Inert cells began to die, their membranes losing integrity, spilling their contents into the water in a slow, cold hemorrhage. Not with a pop, like when Andy killed them. More of a sad little pfsssh, like a balloon three days after the party.

  Mass extinction event. Happening all around him. Very casual Tuesday in the primordial pond.

  [ENVIRONMENTAL EVENT: THERMAL SHIFT (COOLING)]

  [AMBIENT TEMPERATURE DECREASING]

  [WARNING: METABOLIC EFFICIENCY REDUCED AT LOWER TEMPERATURES]

  [SURVIVAL ADVISORY: SEEK THERMAL REFUGE]

  The cold reached for him, his metabolism beginning to lag, and for a panicked moment he was back in the amoeba encounter, that same full-body alarm screaming move, move, move.

  Thermal refuge. The System had said to seek thermal refuge. The surface was cooling first, which meant deeper was warmer, which meant down, toward the thermal vents at the bottom he'd noticed during early hunting but ignored because why commute when the office was right here?

  He dove. Or rather, he sank with intention, dragging himself downward with pseudopods (he had chosen spike over speed, and for the first time, the cost of that choice hit him), past the dying cells, past the slowing predators, past the layer where the temperature dropped from "comfortable" to "uncomfortable" to "your metabolism is going to shut down in ninety seconds."

  The sediment was warmer. The thermal vents radiated a steady heat that felt, against his cooling membrane, like climbing into a bath after being caught in the rain. He nestled into the soft silt between two mineral deposits, horn pointed outward (defensively, habitually, the way a person sleeps with a baseball bat by the bed after watching a horror movie), and waited.

  [THERMAL REFUGE: LOCATED]

  [METABOLIC EFFICIENCY: STABILIZING]

  The cold continued above him, distant, the way you feel weather through a window. The upper pond was dying. Millions of cells bursting in the cold, a vast, silent catastrophe. Pfsssh. Pfsssh. Pfsssh. The saddest sound Andy had never actually heard, happening everywhere at once.

  He stayed there for what felt like a long time. The thermal vents pulsed. The sediment was gritty but warm. Occasionally a dead cell drifted down from above and Andy absorbed it, because waste not want not, and because the XP still counted.

  [SURVIVAL BONUS: +8 XP]

  [ENVIRONMENTAL EVENT SURVIVED: THERMAL SHIFT]

  [NOTE: ORGANISMS THAT SURVIVE ENVIRONMENTAL EVENTS GAIN ENHANCED ADAPTABILITY. YOUR THERMAL TOLERANCE HAS INCREASED.]

  Eight XP for surviving. Generous. The System rewarded not just killing but enduring. Any game that paid you for not dying was a game about living, and Andy was, despite everything, very interested in living.

  [XP: 58/100]

  When the cold receded (slowly, the way a fever breaks), Andy emerged from the sediment and found a changed pond.

  The ecosystem had been pruned. Violently, indiscriminately, the way a blizzard prunes a forest. The upper water was sparse now. Survivors scattered and disoriented. The chemical signatures of the dead forming a nutrient-rich haze that would feed a new generation that would never know they were floating on the graves of billions.

  Circle of extremely microscopic life.

  In the quiet that followed the catastrophe, in the eerie chemical stillness of a pond that had lost most of its inhabitants and not yet replaced them, Andy thought about Megan.

  The thought arrived uninvited, the way thoughts about the dead arrive among the living and thoughts about the living arrive among the dead, without permission and without preamble. He thought about Megan standing in her apartment, checking her phone, the fire emoji sent and the response not received, the door not knocked on, the evening not unfolding the way she had planned. He thought about the call she would have made (to his phone, ringing in his pocket, ringing next to the condom, both equally useless now). He thought about the moment someone would have told her: Andy Snodgrass, the guy she had been dating for three months, the careful, sweet, slightly awkward guy who checked his pocket four times and looked both ways and showed up when he said he would, was dead. Hit by a truck. Crosswalk at Meridian and Tenth. Signal was green.

  He thought about whether she had cried.

  He thought about whether she had been angry.

  He thought about whether she had stood at her window and thought "where are you" and not known that the answer was "dying" and then "dead" and then "a single-celled organism in a pond on a planet that isn't Earth, hunting bacteria with a horn."

  The thought was a whirlpool. He let himself feel it for exactly as long as it took to acknowledge that the feeling was real and the loss was real and the person he had been was gone in every way that mattered to the people who had known him, and then he stopped.

  Not because the feeling stopped. He just chose to stop following it.

  Forward. Only forward. Backwards was a crosswalk and a green signal and a girl with eleven freckles and a fire emoji, and none of it was reachable.

  Andy Snodgrass would not die of self-pity. He had already died of a truck and that was sufficient.

  He turned his spike toward the nearest living cell in the post-catastrophe pond, noted its chemical signature (small, weakened, easy prey), and resumed The Loop.

  [XP: 71/100]

  * * *

  The hunting was good in the aftermath. Fewer predators meant less competition, and the nutrient haze from the dead had created a microscopic buffet attracting survivors from the deep. But the things that had survived were, by definition, the things tough enough to survive.

  Andy was one of those things. So were his prey. The kills got harder. Less pop, more crunch as he hit tougher membranes.

  He adapted. The Snodgrass Special needed modification when targets were faster, more alert. He developed a new technique: park near a nutrient concentration, retract his pseudopods, minimize his chemical footprint, wait. When something came to the food, he struck from stillness. Thwip. Pop. Splorch. Clean. Fast. Efficient.

  He called it "The Patience." Terrible name for an attack. Pretty good name for a life philosophy. He used it to clear the remaining twenty-nine XP with a steady, workmanlike efficiency that his veterinary school instructors would have found deeply concerning and his gaming buddies would have found deeply impressive.

  [XP: 97/100]

  [XP: 98/100]

  [XP: 99/100]

  One more. The last kill before Tier 2. He selected his target with the careful deliberation of a man choosing the final bite of a good meal: a plump, oblivious cell drifting past a mineral outcrop, radiating contentment and dissolved sugars, completely unaware that it was about to become a milestone.

  He lined up the spike. Extended a pseudopod for stability. Took aim (a generous term for chemical orientation but it was the principle of the thing).

  "The horny prokaryote," he narrated one final time, savoring the bit that had kept him sane through a mass extinction and a grief spiral and forty-seven individual acts of microscopic violence, "prepares for its final hunt at this tier. Note the horn, now visibly larger than at initial development, thick and proud and gleaming with what this narrator chooses to interpret as righteous purpose. The prey does not flee. The outcome is foregone."

  He struck. Pop.

  The biggest, most satisfying pop yet. He swore he felt that one in places he didn't technically have.

  [ORGANISM DEFEATED]

  [XP: 100/100]

  [TIER 2 EVOLUTION AVAILABLE!]

  Andy allowed himself one moment of genuine, uncomplicated satisfaction.

  He had survived the tutorial.

  Whatever came next, wherever the skill tree branched, he was ready. He had a horn and a strategy and a deeply inappropriate sense of humor and the certainty that somewhere, at the top of this absurd evolutionary ladder, there was a form waiting for him that had hands. And maybe, if the universe had any sense of poetic justice, other parts too.

  [CHOOSE YOUR EVOLUTIONARY PATH]

  [THIS CHOICE IS PERMANENT AND WILL DETERMINE YOUR ORGANISM TYPE FOR TIER 2.]

  The options shimmered into focus, and Andy Snodgrass, horny prokaryote, the most well-endowed single-celled organism in the pond, leaned in (metaphorically, because leaning required a skeleton) to read.