"Games shouldn't just be about 'fun.' They should also be art, creation, communication, and mutual understanding." - Hideo Kojima

  Sam, the character that players control, receives his first delivery order: a smart drug supplement that provides the brain with oxytocin. This hormone is known for its role in childbirth, breastfeeding, and social bonding. These oxytocin smart drugs, as in the setting, helps these isolated individuals cope with the stress that came from a lack of interpersonal connections.

  A key gameplay element that is emphasizing oxytocin emerges when players connect to the Chiral Network, the game's multiplayer system. They begin to discover structures and items left behind by other players. These installations, including roads, bridges, and ladders, either expedite deliveries or provide shelter from threats. Players who construct these helpful structures receive "likes" from others who benefit from them. Building upon the precedent set by messages in Souls-like games, these interactive features forge bonds of trust between isolated players, stimulating oxytocin release through both the game's narrative framework and scientific reality.
  The game's main human antagonists, known as MULEs or homo gestalts, are former deliverymen who became addicted to oxytocin, to the feeling of being needed and appreciated when making deliveries. Their dependency on the oxytocin rush drives them to attack players to steal cargo, then make the deliveries themselves to receive likes.
  Oxytocin is known for its significant role in social bonding, emotional regulation, and trust. It is often associated with behaviors related to maternal care, romantic relationships, and overall social interactions. Numerous studies have shown that oxytocin can enhance prosocial behavior, increasing the likelihood of cooperation, empathy, and assistance among individuals. This hormone's effects contribute to the formation of social connections and can influence emotional responses in various contexts. When we trust and help each other, and then receive a positive response from them, we will get a higher oxytocin level. This higher oxytocin level will lead us to more mutual help actions.
  This emphasis on oxytocin as the rewarding system distinguishes it from traditional games that keeps players attracted through dopamine. While oxytocin focuses on social interactions and the fulfillment derived from helping others, dopamine is linked to the desire for more rewards. Brain dopamine activation specifically enhances cue-triggered "wanting" for an immediately available reward. These cues are very powerful at eliciting desire and addictive relapse.
  Dopamine is a neurotransmitter in the brain that plays a central role in the reward system including pleasure, motivation, and reinforcement learning. In fact, dopamine is most active when there is a potential for reward, or when an individual expects a pleasurable outcome, not only when the reward is actually received. Neurons increase activity level when unexpected rewards or the cues of rewards occur (Cox & Witten, 2019, p. 483). It will never make you feel truly satisfied as it drives players to keep playing in the pursuit of more rewards.
  Dopamine activation is a cornerstone of many gameplay designs, deeply embedded in the psychology of player engagement. At its core, dopamine is the neurotransmitter responsible for pleasure, reward, and motivation. Game designers leverage this natural mechanism by creating systems that trigger immediate and frequent feedback, which keeps players hooked. The concept of immediate feedback is especially powerful in gameplay because it aligns perfectly with how our brains process rewards. When we receive instant positive reinforcement for our actions, our brains release dopamine, creating a cycle of positive reinforcement that encourages continued play.
  League of Legends demonstrates how traditional games leverage the dopamine reward circuit in our brain to keep us engaged in the play. For every "last hit" made, every enemy champion slain, and every skill shot that lands, players receive immediate feedback. This can come in the form of visual cues (like the flashing of skill effects or the destruction of enemy turrets), auditory cues (the satisfying sound of a kill or a critical hit), and often numerical feedback (gold earned, level-up progress). These rewards are small but constant, keeping players motivated and engaged throughout the game. The sound and visual effects associated with attacks and abilities ensure that every action is not only effective but also acknowledged, reinforcing the player's sense of accomplishment.
  Gacha games leverage the brain's reward system through a sophisticated application of randomness and variable reinforcement, directly paralleling B.F. Skinner's experiments with rats in his eponymous Skinner box. These games employ random "rolls" for in-game items, creating a cycle of anticipation and excitement that optimally triggers dopamine neuron activity - a response that studies show is most pronounced during uncertain outcomes. Just as Skinner's rats pressed levers without knowing when they would receive food rewards, gacha players repeatedly perform "10-rolls" for coveted SSR (Super Super Rare) cards, their behavior maintained through the same unpredictable reinforcement schedule. This system exploits behavioral psychology principles, with the anticipation of uncertain rewards triggering heightened dopamine release, ultimately creating an engaging yet potentially addictive gaming experience that keeps players in a state of eager anticipation.

  Another example of utilizing unpredictability for heightened dopamine response is observed in roguelite games such as Dead Cell, Hades, and Isaac. These games are often structured around procedurally generated content, where each playthrough is unique due to randomization of levels, enemies, and item placements. This randomness is not just a method of keeping things fresh to avoid repetition; it also plays into the player's anticipation and excitement. The lack of predictability creates an uncertain environment where players never know exactly what's coming next, heightening the dopamine response.
  This unpredictability and reward system are linked to another powerful psychological principle: the illusion of control. In many games, even though the outcomes may be random, players feel as though their actions have an impact on the game world. This combination of uncertainty and agency—coupled with the steady stream of rewards—creates a compelling loop of motivation that is difficult to break.

  Oxytocin, dopamine, serotonin, and endorphins together are known as DOPE–"feel good hormones." When dopamine's urge fades away, our mental status is sustained by these other neurotransmitters. If we lack enough of the other hormones to compensate, we will drop into the loop of anxiety and depression.
  Common game-related behaviors might also affect our secretion of neurotransmitters. When we stay up late and get exposed continuously in a bright environment, the habenula nucleus in our brain will activate and release GABA, an inhibitory neurotransmitter that suppresses the production of serotonin. Thus, when we are enjoying ourselves in late night gaming, phone-scrolling, or similar actions that provide dopamine, we are at the same time destroying our serotonin system.

Serotonin influences various behaviors and functions, such as mood, aggression, impulsivity, and feeding, all linked to reward mechanisms. A serotonin deficiency contributes to conditions like depression, anxiety, and mania. While only 10% made in the brain, serotonin can also influence certain behaviors observed in gaming, though its role is less significant in shaping specific game types. Recent research from Dartmouth university shows that serotonin release level is positively correlated with the subjective value of the reward (Spring & Nautiyal, 2024, p. 1). Thus relating to activities like gaming, higher achievement and recognition will elevate the serotonin level. Based on these results, we could infer that when we reach a higher level goal in the game, or comparatively have a high ranking of gaming skills, our serotonin level would increase.

  While the aforementioned hormones are related to positive reward systems, there is a hormone that plays a role with our neural pain circuit–endorphin. Endorphins are neurotransmitters released by the pituitary gland and hypothalamus in the brain. They can alleviate pain, lower stress, improve mood, and enhance your sense of well-being. Also known as "endogenous morphine," it is a natural painkiller that mimics morphine's effects. When there is a strong physical or psychological pain, the brain will release this neurotransmitter to reduce the pain. A few seconds after releasing, the individual can escape from the pain temporarily and feel relaxed. This mechanism may explain why gaming, as a stress-relief activity, can evoke a sense of comfort and escape for individuals seeking a break from real-world pressures.

  In addition, physical exercise is one of the most effective ways to trigger endorphin release. Thus exercise-based games on platforms like Nintendo Wii and Switch can promote physical activity while engaging the player in an interactive and enjoyable way. This could explain the growing appeal of fitness gaming for individuals looking to combine relaxation, fitness, and mental well-being.

  The intricate dance of neurotransmitters in gaming reveals a complex landscape where different design philosophies can profoundly impact player experience and well-being. While traditional game design has largely focused on dopamine-driven mechanics, Death Stranding's innovative approach highlights the potential of strandlike games. This shifts from trapping players into the dopamine loop to an experience of social connection and mutual aid, suggesting a promising evolution in game design and gaming’s effect on players’ brains.
  The balance of these neurochemical systems—dopamine's drive for achievement, oxytocin's social bonding, serotonin's sense of satisfaction, and endorphins' resilience to challenge—creates a more complete and potentially healthier gaming experience. As our understanding of these mechanisms deepens, game designers have an opportunity to craft experiences that not only engage players but also contribute positively to their neurochemical well-being.
  Looking forward, the most successful games may be those that thoughtfully integrate multiple neurochemical pathways, creating experiences that satisfy our immediate desire for achievement while fostering meaningful social connections and lasting satisfaction. This holistic approach to game design could help mitigate the risks of dopamine-driven addiction while promoting more balanced and fulfilling player experiences. In an increasingly digital world, such considerations may become crucial not just for game design, but for our collective mental health.

1. Cox, J., & Witten, I. B. (2019). Striatal circuits for reward learning and decision-making. Nature Reviews Neuroscience, 20(8), 482–494. https://doi.org/10.1038/s41583-019-0189-2 

2. Spring, M. G., & Nautiyal, K. M. (2024). Striatal Serotonin Release Signals Reward Value. The Journal of neuroscience : the official journal of the Society for Neuroscience, 44(41), e0602242024. https://doi.org/10.1523/JNEUROSCI.0602-24.2024