Seller + buyer experience · 0→1
Mystery Box at a glance
A seller lists everything that could be in the box and marks the best ones as hot items. Buyers bid in an auction, and each winner gets one item picked at random, revealed live on stream.
Outcome
In ten months, Mystery Box went from a LIVE-only experiment to one of Palmstreet's biggest ways to sell.
of platform GMV, up from 0.4% at launch
- of all orders, up from 0.5%
- of buyers bought a box, up from 1.3%
- more boxes sold per month
Launch month vs. ten months later, for the whole format.
Overview
Sellers kept asking for a fun way to sell with surprise, and some top sellers held off on joining Palmstreet because we didn't have one.
My role
Research
What sellers needed, and how other apps run games.
MVP
Creating a box, running it on LIVE and the reveal, for sellers and buyers.
Hold the Mystery
An update to build suspense: reveal one by one or all at once, when the seller's ready.
Quick Spin
An update to keep the play moving: a faster reveal for big lots.
Formats
Made every combination of formats clear for sellers and buyers.
Branding
The original Mystery Box look, which other designers later built on.
I worked with my PM, the CTO, the design lead and engineering.
Context
What's a Mystery Box?
A blind box at a toy store, run live. Every order gets a real item. The fun is not knowing which one.
- 1
Build the box
The seller adds every possible item and marks the best ones as hot items.
- 2
Run auctions
Each paid order gets one item from the box.
- 3
Reveal
Everyone watching sees which item the winner got.
Goal
A fun, fair way to sell with surprise that keeps buyers watching, coming back and bidding again.
- Why it mattered
- Viewers stay longer and come back for the next box.
- Hot items give buyers a reason to bid again.
- Sellers make more per hour of LIVE, and get a reason to choose Palmstreet.
- Constraints
- Every order gets a real item. It's not gambling.
- No dollar values on items.
- The system picks every result, never the seller.
- Launched invite only.
Research
What sellers were missing
Before Mystery Box, sellers made do with regular listings: one listing per surprise item, and tracking winners themselves.
Too much setup
A separate listing for every item, just to run one game.
Tracking by hand
Keeping count of what's left and who won what, mid-LIVE.
No way to show what's special
Nothing told buyers a hot item was in the mix.
Hard to trust
Buyers couldn't see how their item was picked.
The MVP answered each one:
- Quick to set up
- Just a name and quantity for each item.
- Tracked for you
- The box counts what's left and who won what.
- Hot items
- Sellers flag their best items, without showing prices.
- Fair by design
- The system shuffles the box and spreads hot items across the sale.
Seller + buyer flow
The MVP
The first version lived inside the LIVE, built on the auction flow sellers already knew.
Seller
One toggle turns an auction into a Mystery Box. Sellers add items, mark the hot ones, pin it and reveal each item once it's sold.
Buyer
Buyers see every possible item and what's left before they bid. After each round, the winner shows on the banner and in the chat.
The reveal
The reveal is the big moment: fast at first, slowing past a hot item, then landing on the winner in about 3 seconds.
MVP
Other states
A few more moments in the MVP I designed for.
At least two items: A Mystery Box needs at least two different items, otherwise there's no surprise.
Phases
How it grew
Mystery Box kept growing after launch. Each phase came from watching how sellers actually ran their shows.
- 1
Dec 2025
MVP
Sell a box on LIVE and reveal each win, with hot items and a fair shuffle.
- 2
May 2026
Manual draw and a new reveal
Sellers using their own randomizer pick each win after the reveal, and the reveal animation got more exciting.
Designed by the team while I was on paternity leave.
- 3
Jun 2026
Hold the Mystery
Sell every box first, then reveal one by one or all at once.
- 4
Jul 2026
Quick Spin
A faster reveal for sellers running big lots.
- 5
Sep 2026
Seller Hub
Every Mystery Box format on desktop, with CSV upload.
Phase 3 · Jun 2026
Hold the Mystery
Every box used to reveal right after it was bought. Buyers often left once they had their result, and sellers couldn't build up to a big moment.
With Hold the Mystery, the seller decides when the reveal happens. Boxes keep selling while results stay hidden, then the seller reveals them one by one or all at once.
- Clear for buyers
- Buyers see their payment went through and their item is waiting to be revealed, with every slot listed in order.
- Control for sellers
- Reveal one by one to keep the show going, or all at once for a big finale.
- Nothing left hidden
- Sellers can't pin another listing until every box is revealed, so no buyer is left waiting.
Phase 4 · Jul 2026
Quick Spin
Sellers running lots of boxes, sometimes hundreds of items, were losing time to the reveal.
Quick Spin swaps the full animation for a short box opening, so sellers can get through large lots fast. They can turn it on when creating the box, or switch it on and off during the LIVE.
Formats
One box, many ways to play
With every phase, a box could now be played several ways. Sellers and buyers both needed to know how this particular box works.
I designed a short explainer for each format, and a How it works for buyers that changes with the box, so the rules always match what's on screen.
Seller and buyer
Every combination
The same box sheet, with its How it works rewritten for each combination. Sellers see how to run it, and buyers see exactly how their win will be picked and revealed.
Seller
Buyer
Phase 5 · Sep 2026
Seller Hub support
As part of Seller Hub LIVE, I brought every Mystery Box format to desktop, so sellers can create, run and manage boxes from their computer. On desktop, sellers can also upload their item list as a CSV or pick a saved template, which speeds up setup.
Screen
Outcome and learnings
Outcome
Mystery Box went from a LIVE-only experiment to 12% of platform GMV and 20% of all orders in ten months, with a big part of that growth coming from the formats that followed the MVP.
of platform GMV, up from 0.4% at launch
- of all orders, up from 0.5%
- of active sellers ran a box, up from 0.7%
- new boxes use Quick Spin, two months after launch
- of new boxes use Hold the Mystery, after peaking near 17%
Launch month vs. ten months later, for the whole format.
Start small, then follow how people use it
The MVP did one thing well: a fair, fun reveal on LIVE. The formats that came after, Hold the Mystery and Quick Spin, came from watching how sellers actually ran their shows, and they drove a meaningful share of the growth.
Buyers turned into sellers
When we talked to our top buyers, we found some were buying boxes to complete their sets. Over time they collected so much that they applied to sell on Palmstreet and started running their own shows.
Speed beat suspense
Quick Spin reached 1 in 4 new boxes within two months and held there. Hold the Mystery peaked near 17%, then settled around 10%. Most sellers wanted a faster show, and a smaller group wanted the build up.
Small buys, often
Boxes became about 20% of all orders but about 12% of GMV. Buyers bought them often at lower prices, which is what a game format should do.
Buyers came along
The share of buyers who bought a box grew from 1.3% to 18.5%, so it wasn't just a few big sellers. It reached a big part of the buyer base.
