не ищите в этом смысла, я просто веселился

joy-cursor.lua

local traceRainbowSpeed = 360 / 2
local traceLength = 360 / 4
local trace = {}
local prevX, prevY = input.GetCursorPos()

local function DrawTrace()
	local x, y = input.GetCursorPos()

	do
		local dx = x - prevX
		local dy = y - prevY
		local dist = math.sqrt(dx * dx + dy * dy)
		local step = 4

		for i = 0, dist, step do
			if #trace == traceLength then
				table.remove(trace, 1)
			end

			table.insert(trace, {
				x = prevX + dx * (i / dist),
				y = prevY + dy * (i / dist)
			})
		end
	end

	prevX, prevY = x, y

	for i, tr in ipairs(trace) do
		local c = (#trace - i + 1) / #trace
		local col = HSVToColor((SysTime() * traceRainbowSpeed + c * 360) % 360, 1, 1)
		local size = 8 + c * 16

		surface.SetDrawColor(col.r, col.g, col.b, 255 - c * 255)
		surface.DrawRect(tr.x - size, tr.y - size, size, size)
	end
end

local radius = 64
local speed = 8

local function MoveCursor()
	local ang = SysTime() * speed
	local x = ScrW() * 0.5 + math.cos(ang) * radius
	local y = ScrH() * 0.5 + math.sin(ang) * radius

	input.SetCursorPos(x, y)
end

hook.Add("HUDPaint", "joy cursor", function()
	MoveCursor()
	if vgui.CursorVisible() then
		DrawTrace()
	end
end)