A cat's journey through a pop-up book.

A five-day exploration

Hikari is a fictional game concept I created as a personal passion project. Over the span of five days, I explored UX/UI design in Unreal Engine 5, experimenting with systems, interaction design and atmosphere.

The game follows a small kitten navigating environments represented as pop-up scenes inside a 3D book. The project is still in progress, but it demonstrates my approach to prototyping, problem-solving and designing interactive experiences.

What I set out to explore

, Explore UX/UI design in a game context.

, Prototype functional systems (menus, interaction, feedback loops).

, Experiment with combining 2D and 3D assets for storytelling.

, Practise localization and input mapping.

, Design and illustrate original props for a consistent visual style.

A book that opens into worlds

The central concept was to design a book that opens into playable environments, inspired by Japanese culture and aesthetics. To bring this to life, I designed and illustrated all the props myself, including the 3D book and paper pop-ups such as the shrine, trees and pickup items.

The focus was less on detailed world-building and more on how the player interacts with the world, navigates, and receives feedback.

Accessibility & playful feedback

The main menu was my first design challenge, I wanted it to demonstrate interactive polish as well as technical implementation in Unreal Engine.

Features: volume control (all audio split into Music or SFX, plus a Master control); a full localization system with multi-language support, currently English and Japanese; keybinding options with conflict resolution when two actions share a key; and animated UI navigation using an animated firefly. This section highlights how I integrated accessibility features and playful feedback into the UI.

The book opens into a scene

Once the player starts, the 3D book opens into an explorable environment. The cat is controlled with a top-down angled camera using sprite animations I created for idle and running states.

Systems implemented: environmental feedback (grass moves and makes sound when walked through); interactive thought bubbles for contextual narrative feedback; pickups with UI pop-ups (e.g. Moldy Onigiri, 5 Yen coin); a rock-pushing mechanic using the enhanced input system for a consistent push action regardless of direction; and a flap mechanism that lifts an environment piece after a puzzle interaction.

Clear, engaging feedback

UI was a major focus. Each system was designed to give players clear, engaging feedback: thought bubbles convey the cat's inner thoughts; pickup pop-ups confirm successful interaction; sparkly Niagara VFX draw attention to collectible items; and subtle animations (the firefly, the book opening) add life and flow to navigation.

Original UI & visual assets

Beyond the UX and systems, I created all the visual assets for this prototype. Every prop and object in the environment was designed and drawn by me, from the run-down shrine to the sparkly pickups, letting me experiment with style across both interactive elements and environmental decoration.

Gameplay demo

A short demo of Hikari showing the main menu interactions, the book opening, and the first playable sequence with the little cat.

Where UX meets gameplay

Hikari was an opportunity to experiment, learn and test how UX and UI design intersect with gameplay systems in Unreal Engine. In just a few days I built a working prototype with a functional menu, localization, sprite animations, environmental interactions and puzzle mechanics.

Future development will focus on expanding the Japanese-inspired environments, adding a storyline for progression, refining the art style and visual consistency, and expanding the interactive mechanics. It's a work in progress, but it reflects my passion for crafting thoughtful, player-centred design.