From Fighting Monsters to Understanding Them: How Undertale Changed My Understanding of Worldbuilding
If someone had asked me after my first hour of Undertale whether I wanted to keep playing, I probably would have said no. The pixel art wasn’t really my style, and I spent what felt like forever wandering around the Underground. I honestly couldn’t understand what all the fuss was about.
Then something shifted. I stopped rushing toward the next area. I wanted to see Papyrus again and understand Toriel. Somewhere along the way, the Underground stopped feeling like a map and started feeling like a place where people actually lived.
Looking back, I don’t think the world changed—I did. Before playing Undertale, I thought worldbuilding came from beautiful environments, detailed lore, or long histories. The game convinced me otherwise. Players buy into a world not because of what it tells them, but because of what it keeps asking them to do. That realization reshaped how I see worldbuilding and how I think about designing games myself.
At first, I approached every battle like a traditional RPG. My goal was simple: defeat the enemy efficiently and keep moving. Then the game started throwing strange alternatives at me: ACT, MERCY, complimenting someone, telling a joke, even flirting. I picked those options out of curiosity at first. During my fight with Papyrus, though, I noticed I was spending more time choosing ACT options than planning how to win. Every joke and conversation revealed another side of his personality. By the end of that battle, I wasn’t trying to beat him—I was trying to help him. The encounter stopped feeling like combat and started feeling like a conversation.
That shift finally made the MDA framework click for me. The ACT mechanic never directly tried to make me care about monsters. It just kept nudging me to pause, observe, and try something different. Repeating those actions changed how I approached each encounter. Instead of asking how to win, I started asking what each character needed from me.
What really caught me off guard was how the game’s formal elements quietly rewired my goals. The rules never removed violence as an option, but winning gradually stopped meaning “defeat the enemy.” Paying attention opened new conversations, relationships, and ways forward. ACT and MERCY taught me what mattered without ever announcing it directly. The objectives, rules, and procedures weren’t just scaffolding for the game—they were broadcasting the values of the Underground.
The narrative reinforced those values through character rather than exposition. Papyrus wants to join the Royal Guard because he craves recognition. Toriel isolates herself because she can’t shake her guilt. Undyne’s hatred toward humans comes from the history and culture she inherited, not from some innate “monster” quality. On the Pacifist route, refusing to attack Undyne made me realize that her anger came from stories she’d been taught rather than from anything biologically monstrous.That friction is what made the Underground feel like a real society with competing values, not just a kingdom populated by interchangeable creatures.
This is also why Undertale stuck with me longer than most JRPGs I’ve played. In those games, enemies are usually roadblocks you clear before getting back to the story. In Undertale, dealing with monsters is the story. I learned about the world through its systems rather than lore dumps.
This hit home when my group started building our own fantasy card game. But we rarely stopped to ask what our mechanics were actually teaching players. We wanted cooperation to be a core value of our world, yet some of our strongest early card combinations rewarded going solo. We therefore redesigned our mechanics to consistently reward cooperation instead of simply describing it in lore.
The game also takes aim at a tired fantasy cliché: the idea that race determines morality. Papyrus, Sans, Toriel, and Undyne all belong to the same race, but their personalities come from relationships, personal history, and social roles—not biology. This makes the Underground more believable while challenging the idea that morality is determined by race.
That said, playing the game also made me think about what I’d do differently. I’d consider tying relationship growth to mechanical progression. Earning a character’s trust could unlock new ACT options or alternative ways to resolve future encounters. That kind of progression would reinforce Undertale’s core message instead of replacing empathy with a traditional power fantasy.
I also wonder whether the Pacifist route sometimes tips its hand too much. Mercy hits hard emotionally, but it’s usually framed as the obviously right call. I’d be more interested in designing situations where several choices feel defensible—where players have to sit with uncertainty instead of hunting for the “good” ending.
Funny to think I almost quit after that first hour. The Underground become interesting because the game changed how I interacted with it. Now I think it’s something players actively learn through the choices a game repeatedly asks them to make. Every mechanic poses a question, and every action becomes part of the player’s answer.
