Open Sauce

Building the Fixed Data Node

The Fixed Data Node was an idea long before there was a box.

In 2023, while we were building the Portable Data Node, we started asking what would happen if PDNs could talk to fixed hardware in the world, not only to each other. That thread became FDN MK I.

The first generation was not built to run four different games. It was built for one job at Neotropolis 2026: symbol matching on player PDNs, two jacks into an FDN at once, one word of a five-word passphrase per successful hack. Deliver the full phrase to the right character and you could claim a pewter coin. Five of seven prototypes survived the desert. The idea worked well enough to take on the road.

Open Sauce was the harder question: could the FDN be a game platform, not just a puzzle prop?

We had about two months and ~50,000 attendees who mostly had never heard of Neotropolis. Neo's implementation was deliberately narrow. San Mateo needed standalone demos strangers could play in ninety seconds.

Four boxes, four games

We brought four FDN MK I units, each running something different:

• Crypt Keeper: tiny dungeon crawler
• Floaty Boat: side-scroller, boat vs obstacles
• Bonk It: Simon Says-style memory
• Quickdraw: single-player take on the duel mechanic

None of these were shipping products. They were probes: what interactions fit the hardware, what could we build fast, and how painful is it to ship a new FDN game from scratch?

Some builds were simple. Some broke on the floor. We were still inventing the pipeline while the booth was open. That is why we went.

Platform, not one game

If the FDN were only the Neo passphrase hunt, we could have stopped after the desert. Open Sauce was the first time we treated it as shared hardware with swappable games: different rules, different screens, same box class.

We are developing the hardware before we chase a huge game library on purpose. First-gen FDN MK I builds stayed in-house, roomy enclosures, swappable parts, no custom PCB yet, so we could learn without locking manufacturing. Neo proved the FDN could sit inside an immersive hunt. Open Sauce proved strangers were curious about it without the LARP context.

Next steps: custom FDN MK II PCBs, better comms, sensors we did not know we needed until these events. Booth story and headcount are on the Open Sauce 2026 event page.

Alleycat in one line: open source hardware for immersive, in-person play. Cyberpunk at Neotropolis is a deployment we love, not the only skin the platform can wear.