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Founding Engineer - Harness Optimization

Pax Historia · San Francisco

Pay
$140k–$220k
Workplace
On-site
Job type
Full-time
Posted

About the role

Founding Engineer - Harness Optimization at Pax Historia in San Francisco. On-site, full-time, paying $140k–$220k. Posted August 22, 2026.

Company

Pax Historia is creating the future of interactive entertainment.

We’re building the platform for worldbuilders, storytellers, and game devs to create and publish any ‘what if’ they can think of. So far, most of the 25k+ user published presets on our site are historical (eg, ‘what if Rome never fell?’), but fantasy and sci fi are the fastest growing categories on the site.

We have seen over 92 million rounds played and raised a 10M+ seed round in March. We’re backed by Y Combinator (W26), Bessemer, Pace Capital, Z Fellows, and more.

Role

Each game on Pax Historia is run by the AI model the user picked to run their game. Games are much more fun if the AI running their game is able to balance long-term internal consistency with creative developments - in short, if the AI is good at storytelling.

But today, we’ve barely scratched the surface of getting the best possible results out of the ~240B tokens processed on our site each week. The same default AI workflows run across very different models, and we haven’t done much to adapt to the quirks of the 37+ models on our site now. We think our games can be much more interesting than they are today, which is why we’re hiring for this role.

On day one, you’d experiment with workflow architecture and prompts to begin making improvements and building the evals needed to figure out whether you’re actually making games better.

You might be a great fit if you’re extremely experiment-driven, a big-picture systems-thinker, and a storyteller yourself. We don’t expect you to have done this exact job before, but we are expecting you to be a fast learner with extremely strong fundamentals.

Logistics

You’ll be our 7th team member. We work in-person in San Francisco, 5+ days/week. We are open to sponsoring visas.

Comp will include meaningful equity to reflect your responsibility as a founding engineer.

Prefer to apply yourself? Apply on Pax Historia’s site

Quick answers

How much does this Pax Historia job pay?

The posted pay is $140k–$220k.

Where is this job based?

San Francisco. The role is on-site.

How do you apply?

Apply on Pax Historia’s site using the link on this page. With a free Jobmagic account you can see how well you fit first.

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