Roblox UI

Implement deliberate, editable Roblox UI that preserves the experience's visual language and works across supported devices. Targets Roblox's rolling platform APIs. Pair with game-ui-ux for engine-neutral information architecture and UX; this skill owns Roblox Instances and APIs.

When to use

• Use for authored ScreenGui interfaces, Roblox layout/constraint APIs, UI lifecycle, input, focus, animation, performance, or responsive/device fixes.
• Use to replace brittle pixel layouts, runtime-created Instance tangles, mouse-only menus, or generic generated styling with a maintainable hierarchy.

When not to use: general UX flow and accessibility principles belong to game-ui-ux; raw gameplay action mapping belongs to input-systems; server trust belongs to roblox-networking.

Workflow

1. Inspect before designing. In Explorer, inventory existing ScreenGuis, UI modules, fonts, colors, icon family, spacing, corners, strokes, animation timing, naming, and reusable components. Capture representative screenshots at two viewports. Extend that language.
2. Define ownership and lifecycle. StarterGui is the authored template; Roblox clones it into each player's PlayerGui. Decide whether each ScreenGui should persist across respawn with ResetOnSpawn = false; never keep stale references to a destroyed clone.
3. Author a readable hierarchy. Prefer meaningful editable Instances and small behavior modules. A normal screen should be understandable in Explorer; procedural generation is for genuinely data-driven repetition, not the whole shell.
4. Build responsive structure. Combine UDim2 scale for placement with bounded offsets, correct AnchorPoints, layouts, padding, content sizing, and constraints. Choose explicit narrow/wide arrangements instead of shrinking a desktop panel until it technically fits.
5. Handle platform obstructions. Keep interactive UI in CoreUISafeInsets (the recommended ScreenGui.ScreenInsets default), and account for touch controls and TV distance/overscan.
6. Wire state and input. Render from a small view state; update on events. Use Activated for GuiButtons, explicit selected states, and reachable gamepad navigation. Bind non-widget actions with ContextActionService only while the screen owns them.
7. Polish with restraint. Implement hover, pressed, selected, and disabled states. Animate state changes, not decoration; honor GuiService.ReducedMotionEnabled and clean up tweens and connections when the screen closes or is replaced.
8. Verify the real interface. Use Device Emulator and Controller Emulator. Test desktop, narrow portrait, mobile landscape, tablet-like, and console/gamepad; then respawn. Record clipping, overlap, text, scroll, safe-area, focus path, touch target, and lifecycle results.

Production structure

StarterGui
└── InventoryGui (ScreenGui; ResetOnSpawn = false)
    ├── Root (Frame)
    │   ├── Header
    │   ├── Content
    │   │   ├── CategoryList
    │   │   ├── ItemGrid (ScrollingFrame)
    │   │   └── DetailsPanel
    │   └── Footer
    └── InventoryController (LocalScript)
ReplicatedStorage
└── UI
    ├── Components
    └── Theme

Names describe roles, not colors or temporary positions. Keep repeated item cells as templates or components, but keep the authored shell visible in Explorer.

Patterns

Layout that survives content and viewport changes

-- Authored properties on ItemGrid (ScrollingFrame):
--   AutomaticCanvasSize = Enum.AutomaticSize.Y
--   CanvasSize = UDim2.fromOffset(0, 0)
-- Children: UIPadding + UIGridLayout
local grid = itemGrid.UIGridLayout
local projectBreakpoint = 700 -- derive from where this composition stops being usable

local function applyComposition()
    local narrow = root.AbsoluteSize.X < projectBreakpoint
    categoryList.UIListLayout.FillDirection = if narrow
        then Enum.FillDirection.Horizontal
        else Enum.FillDirection.Vertical
    categoryList.Size = if narrow
        then UDim2.new(1, 0, 0, 40)
        else UDim2.new(0, 148, 1, 0)
    itemGrid.Position = if narrow then UDim2.fromOffset(0, 52) else UDim2.fromOffset(164, 0)
    itemGrid.Size = if narrow
        then UDim2.new(1, 0, 1, -52)
        else UDim2.new(0.58, -164, 1, 0)
    detailsPanel.Visible = not narrow -- open details as a separate narrow-screen state

    local width = itemGrid.AbsoluteSize.X
    local columns = if width < 520 then 2 elseif width < 820 then 3 else 4
    local gap = 12
    local usable = width - itemGrid.UIPadding.PaddingLeft.Offset
        - itemGrid.UIPadding.PaddingRight.Offset - gap * (columns - 1)
    grid.CellSize = UDim2.fromOffset(math.floor(usable / columns), 112)
    grid.CellPadding = UDim2.fromOffset(gap, gap)
end

root:GetPropertyChangedSignal("AbsoluteSize"):Connect(applyComposition)
applyComposition()

Use UIListLayout for one-dimensional flow, UIGridLayout for uniform cells, and UITableLayout only when row/column alignment is truly tabular. AutomaticSize fits content; AutomaticCanvasSize fits scroll content. Bound extremes with UISizeConstraint, UIAspectRatioConstraint, or UITextSizeConstraint rather than one global UIScale guess.

One activation path and explicit gamepad entry

local GuiService = game:GetService("GuiService")
local RunService = game:GetService("RunService")
local UserInputService = game:GetService("UserInputService")

local function openInventory()
    root.Visible = true
    task.spawn(function()
        RunService.RenderStepped:Wait() -- selection must be rendered and selectable
        if root.Visible and (UserInputService.GamepadEnabled
            or (UserInputService.KeyboardEnabled and not UserInputService.TouchEnabled)) then
            GuiService.SelectedObject = firstItemButton
        end
    end)
end

local function closeInventory()
    GuiService.SelectedObject = nil
    root.Visible = false
end

firstItemButton.Activated:Connect(function()
    selectItem(firstItemButton:GetAttribute("ItemId"))
end)

Prefer Activated over separate mouse/touch handlers. Set NextSelectionUp/Down/Left/Right when automatic navigation is ambiguous, especially around grids, sidebars, and modals. A modal must trap focus inside itself and restore a sensible selection when it closes.

For cross-device action binding, the Input Action System (InputContext/InputAction/ InputBinding) is the modern edit-time layer; see references/input-navigation.md.

Inspect Roblox's default selection adornment in context. If it overwhelms the interface, assign a project-owned SelectionImageObject or selected-state treatment; keep it visible, valid, and restrained rather than disabling focus feedback.

State transition without animation noise

local TweenService = game:GetService("TweenService")
local GuiService = game:GetService("GuiService")
local fade = TweenInfo.new(0.14, Enum.EasingStyle.Quad, Enum.EasingDirection.Out)

local function setPanelVisible(visible: boolean)
    panel.Visible = true -- panel is a CanvasGroup
    if GuiService.ReducedMotionEnabled then
        panel.GroupTransparency = if visible then 0 else 1
    else
        TweenService:Create(panel, fade, {
            GroupTransparency = if visible then 0 else 1,
        }):Play()
    end
    if not visible then
        task.delay(fade.Time, function()
            if panel.GroupTransparency == 1 then panel.Visible = false end
        end)
    end
end

Animate a panel or state boundary once. Do not independently bounce every descendant.

Visual quality gates

• Establish hierarchy through size, weight, contrast, grouping, and whitespace before adding decoration. Use a small spacing scale and align to it.
• Preserve the game's fonts, palette, icons, radii, and strokes. If none exist, define a compact token module; do not improvise per component.
• Use corners where the material/form calls for them, not on every nested Frame. Avoid nested card-on-card shells, universal pills, arbitrary gradients/glows/shadows, neon outlines, excessive transparency/blur, oversized headings, meaningless icons, and huge empty panels.
• Buttons with different importance should not look identical. Define primary, secondary, quiet, destructive, selected, pressed, hover, and disabled treatment only as needed.
• Motion communicates open/close, focus, confirmation, or spatial relationship. Keep it short, interruptible, and subtle; avoid perpetual motion and decorative tween chains.
• On touch devices, reserve the default movement/jump corners. Move or recompose bottom actions that overlap them, and hide keyboard/gamepad hints when those inputs are not active.

Common failures

Symptom	Likely cause	Remedy
UI disappears or duplicates after respawn	wrong ResetOnSpawn policy or stale clone	choose policy; reacquire from PlayerGui; clean old bindings
Phone layout clips	desktop offsets/global scale used as layout	add narrow composition, layouts, bounds, and Device Emulator checks
Content hidden under topbar/notch	insets ignored or ScreenInsets = None	use CoreUISafeInsets for interactive UI; inspect intentional bleed
Scroll ends early	fixed CanvasSize	use AutomaticCanvasSize or layout AbsoluteContentSize
Controller gets stuck	no entry selection or bad neighbor graph	set initial SelectedObject; define and test focus edges/modal trap
UI looks generated	decoration substituted for hierarchy	remove effects; align, reduce nesting, fix density and component roles
Explorer contains only one script	entire authored interface is procedural	author the shell as named Instances; generate repeated content only
Increasing connection/tween count	screen rebinds without cleanup	own connections per screen lifecycle; disconnect/cancel on teardown

Resources

• Read references/responsive-layout.md for layout decisions, inset policy, density, and the required viewport matrix.
• Read references/input-navigation.md when implementing gamepad/touch focus, modal behavior, action binding, or motion preferences.
• Build assets/inventory-quality-test.project.json with Rojo (it maps the adjacent JSON model) for an editable Instance fixture used in visual/layout review; it is a test baseline, not a style template for a shipping game.

Related skills

• game-ui-ux — information hierarchy, screen flow, accessibility, and UX validation.
• input-systems — gameplay action mapping and device switching.
• roblox-networking — server-authoritative requests initiated by UI.
• roblox-studio-workflow — Explorer-first editing and Studio verification.

Primary references

• Roblox Creator Hub: https://create.roblox.com/docs/ui/on-screen-containers
• Roblox Creator Hub: https://create.roblox.com/docs/ui/position-and-size
• Roblox Creator Hub: https://create.roblox.com/docs/ui/size-modifiers
• Roblox Creator Hub: https://create.roblox.com/docs/studio/testing-modes