A developer building a space-game player economy laid out the rules in four lines, then asked r/gamedesign what those rules do to everything else in the game.
- Every HQ sells an item at a fixed price — call it 100.
- Every HQ buys it back at 50, from anyone, at any time.
- Each HQ has a storage cap. Full means it stops buying.
- Restocking is manual.
Player-to-player prices live in the corridor between 50 and 100 — and both walls can fail. A stock-out removes the ceiling, so whoever stockpiled sets the price. A full HQ removes the floor, stranding anyone still holding inventory.
The real problem is the third exit. Raw elements can also be refined or consumed in synthesis, which makes the 50 buyback the opportunity cost of every crafting decision: any recipe returning less than selling its inputs to the vendor will never be run, however interesting its output.
The answers from the thread are concrete:
- Let vendors buy higher as stock depletes, so the floor carries information about scarcity instead of being a static number.
- Post hauling contracts between hubs — a full station pays players to move stock to an empty one — so shortages read as consequences of player activity rather than an admin’s mood.
- Only the finished item has to beat the floor: ore to bar can lose value if bar to sword more than makes up for it.
- The provocation underneath all of it: without destruction or loss creating ongoing demand, players have no reason to trade at all.
The part worth stealing is the framing, not the numbers. A guaranteed NPC buyback price is not a neutral newbie safety net — it sets a hard value under every input in your crafting tree and quietly decides which recipes can exist. The lever is not whether to have a floor, but whether the floor is fixed or informative.