Lead Product Designer

Design

Lead Product Designer

Shape the design of a generative learning world

London (Euston) In person Equity £100–150k

Contact: ***email_hidden***

We're second-time founders and former Google and Synthesia leaders (Search, Voice, and Assistant). We're assembling a core team of engineers, artists and educators to build the interface between AI and childhood.

In March 2026 we raised a pre-seed round led by Jeff Dean (Chief Scientist, Google DeepMind and Google Research), alongside world-class angels and investors. 12,000 families joined our waitlist organically, without us spending a single dollar on marketing, and we released our first beta in July. We’ll be part of Y Combinator’s Winter 2027 batch.

The problem we're solving

Kids spend hours every day with digital products, but most of those experiences are passive, repetitive, or optimized for attention rather than development. Parents want something safe, genuinely engaging, and educationally positive. Kids crave play and agency; parents crave growth and trust. The industry still hasn't bridged that gap.

Our product

Marble is building the first generative learning world. If you’ve read the Diamond Age, you know what that means. If you haven’t, this video will bring you up to speed.

Marble is a 3D adventure game built in Unity and released on iOS and macOS. Children explore a world populated by a cast of AI characters they interact with through voice. Conversations are open-ended, not scripted. The characters create stakes and narrative, while the world offers children agency and the opportunity to chart their own course.

We are building a product and a brand founded on trust and craftsmanship. The world building, the visuals, the sounds, the UI/UX … they’re all a way to communicate to a parent that the people behind the product really care about their child’s experience.

Founders

Guillaume (CPTO): First product hire at Synthesia, where he scaled from $3 to $100M ARR and helped define the category of AI video. Spent 7 years at Google as a PM on Search. Dad of two (ages 7 and 9), giving him a front-row seat to what captivates and educates kids today.

Lio (CEO): Second-time entrepreneur: founder of Neoplants, raised $25M+ from top-tier US investors. Ex-Google PMM, part of the original Google Assistant EMEA launch team (2017). Creative technologist and product builder with 15 years across tech, storytelling, and consumer launches.

About You

You think of yourself as a pirate. Wait, maybe that’s too specific. A bear will do too. The point is, you want to bring something special to this world. Something wonderful.

In corporate speak, we might say that we're looking for an ambitious and forward looking Product Designer who's excited at the prospect of inventing a new consumer product category with AI at its core. You’re comfortable working on a product with a lot of ambiguity, where things remain to be invented and defined. You have a broad set of skills, and can jump from visual work to diving deep into subtle UX trade-offs. You’re comfortable implementing your own designs, and relish the control it gives you. You've worked on world class product experiences before. You have strong tastes.

What we’re looking for, really, is someone who wants to shape visual language and culture, and leave a mark on the world.

The role

As Marble’s lead product designer, you will be responsible for our product craft, in all its dimensions. You will own the UX, the UI, the visual design and the motion and turn ambitious features into wonderful experiences. You will define the overall design language of the product and evolve it as needed. You will implement your own designs and shape a substantial part of the product client codebase, with support from the engineers on the team.

You will work in close collaboration with the founders on strategic product and marketing directions and help define a new class of experiences, at the intersection of gaming, media and AI.

Requirements

You have

• A portfolio of shipped products that demonstrates exceptional visual and interaction design. You can show what you personally shaped, explain the decisions behind it, and point to details that made the experience better.
• A distinctive visual sensibility, grounded in strong fundamentals: typography, composition, colour, hierarchy and motion. You can create a coherent design language and carry it through to the smallest interaction.
• Strong product instincts. You can turn an ambiguous idea into an experience that feels simple and intuitive, and make thoughtful trade-offs between user needs, technical constraints and the ambition of the product.
• The ability to build what you design. You’re comfortable writing and iterating on client code, using AI tools where useful, and working with engineers to bring your designs into the shipped product.
• A feel for motion and interaction beyond static screens. You can prototype transitions, feedback and timing, and refine them until the experience feels responsive, expressive and satisfying.
• Experience taking meaningful ownership from early exploration through launch. You can set a direction, explain your reasoning, and bring others with you while remaining open to a better idea.

You’re comfortable with

• Moving between product direction and detailed execution. In a small team, you might explore a new interaction one day, refine the visual language the next, and implement it the day after.
• Designing for children and their parents. You’re curious about how children think, play and learn, and willing to test your assumptions by watching them use what you’ve made. You care about agency, clarity and trust.
• Inventing interactions around AI. Voice, unpredictable responses and open-ended experiences are design material you’re excited to explore. You can make unfamiliar capabilities understandable and help users recover when things go wrong.
• Working with incomplete information. You know when a rough prototype will answer the question, when to invest in polish, and how to revise your direction after putting something in people’s hands.

Nice to have

• Experience with Unity and C#, or another game engine.
• An extensive gaming culture.
• Work on games, playful consumer products, voice interfaces or generative AI experiences.
• Experience designing for children or families.
• Work in brand design, illustration or creative coding that shows the breadth of your taste and interests.

Work conditions

• Salary up to 100k-150k GBP depending on experience
• Strong equity component
• In person work from London Euston

Sound like you?

Get in touch at ***email_hidden***.