Picture opening your shop's doors for the first time. Three customers walk in. One buys the sword you bought yesterday, another haggles for a potion, and the third wants something you don't have yet. By the end of the week you know what the town buys. You start stocking smarter.

Summer Engine helps you build the inventory system, customer AI, pricing mechanics, shop upgrades, and town economy through conversation. You design the shop type and its world. The AI scaffolds the systems that make running a shop feel like a puzzle with real stakes.

Shop sims work because they make players feel clever when they figure out the market. The customer who overpays because they need it urgently. The rare item you bought cheap and sold for ten times the price. Design those moments deliberately.

• Designers inspired by games like Moonlighter, Recettear, or Shop Titans who want to build their own shop sim.
• Teams building a fantasy or RPG world with an economy players can manipulate through smart trading.
• Solo devs creating a mobile idle shop game with active sessions and passive income.
• Anyone who wants to build a game around the merchant fantasy.

• Shop Loop Prototype

  Build the core buy-stock-sell loop with customer AI, a basic pricing system, and enough inventory variety to test balance.

• Full Shop Management Game

  Create a complete shop sim with 50+ items, customer personality types, staff hiring, shop upgrades, and a town economy to exploit.

• Adventure Shop Hybrid

  Build a game where players venture out to acquire items and return to sell them in their shop: the Moonlighter formula.