Tycoon — plot claiming, income loop and persistence

What it is

A server-authoritative Roblox tycoon: atomic plot claiming, a single server-driven income loop, and DataStore persistence that survives a mid-session failure — no client-side script decides what a player owns or can afford.

Under the hood

Claiming a plot looks trivial — check if it’s free, assign it — until two players trigger their ProximityPrompt in the same frame. claimPlot runs synchronously to completion with no yield in the middle: Luau’s single-threaded execution model means the read-then-write (check plotOwners[plot], then set it) can never be interleaved by another player’s claim. That’s the whole trick, and it only holds because nothing in the function awaits anything.

Income is server-driven on a fixed interval rather than accumulated client-side and reported back — the client has no code path that increases its own cash. Droppers are looked up in a server-owned catalog the same way shop items are: id in, price and income out, never trusted from the client. Progress is saved per player on leave and on BindToClose, and — same pattern as the shop system — a failed DataStore:SetAsync is retried rather than silently dropped, because losing a session’s income to one transient error is a worse experience than a slightly slower save.

-- Server-side source of truth. Client never decides what it owns or what it can afford.
local DROPPER_CATALOG = {
	BasicDropper   = { price = 0,    income = 1  }, -- free starter dropper
	FastDropper    = { price = 250,  income = 3  },
	PremiumDropper = { price = 1000, income = 10 },
}

local function claimPlot(player)
	if playerPlots[player.UserId] then
		return -- already owns a plot
	end

	local plot = findOpenPlot()
	if not plot then
		return
	end

	plotOwners[plot] = player.UserId
	playerPlots[player.UserId] = plot
	plot.Owner.Value = player.Name

	local progress = loadProgress(player)
	playerCash[player.UserId] = progress.cash
end