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Kantrip
EngineeringLondon · In personFull-time

Founding AI Engineer

Own the agent system that turns a game spec into a shipped game, along with the evals, the model routing and the runtime underneath it.

The role

We're building an agent system that turns a game spec into a shipped game. We have a working system but we know it can always be better. You own that system and where it goes next, we can't just use off the shelf system, games need specific loops, context and the economics matter.

Model releases lift everyone equally. You'll be building the system that turns those models into games people want to play. You work with the founder and our engine and platform teams to build agents that bridge the gap between prompt and playable.

What you'll do
  • Design, build and operate the pipeline that takes a game from spec to shipped build: planning, code generation, review and release.
  • Build evaluation and regression tooling that measures output quality and catches failures automatically.
  • Build the routing layer that selects a model for each pipeline step based on quality, latency and cost.
  • Replace third-party agent infrastructure with our own runtime where that improves quality, control or cost.
  • Build our retrieval and context systems, and lead fine-tuning of models on the data the platform generates.
What we're looking for
  • You follow the field closely and test new models and techniques as they're released.
  • You've built LLM systems in production: multi-step pipelines, tool-using agents, or eval infrastructure.
  • Strong systems engineering background. We work in TypeScript; deep experience in another language is fine.
  • You've designed and run evals: test sets, benchmarks, regression tracking.
  • You've managed inference cost alongside quality and latency in a production system.
  • Based in (or willing to relocate to) London. We work in person, five days a week, from our office in Bloomsbury.
Bonus
  • Model routing or gateway infrastructure.
  • Fine-tuning, post-training, or retrieval systems.
  • A background in games.
Think this is you?Send an emailor email careers@kantrip.dev

How we hire

We keep it short, we pay for your time, and you know the bar at every stage.

01 · Intro call
30 minutes. What we are building, what you have built, and whether to keep going. Either side can stop here.
02 · Technical walkthrough
60 minutes. You walk us through the best thing you've built: your code, your screen.
03 · Paid exercise
£250 flat, 2 to 4 hours, done in your own time within a week. AI tools allowed and expected: that's how we build. The pass criteria are stated upfront. Followed by a 30-minute debrief on how you approached it.
04 · Coffee
In person in London, plus references. Then we decide.

End to end in about two weeks.