What makes a Roblox thumbnail click

How to make Roblox game thumbnails that get clicked: what the image has to do, a reusable prompt system for AI image models, the two generation pipelines we used (and their traps), and small tools for picking prompts and reviewing results.

Distilled from a few rounds of real thumbnail work: about 60 images for a strategy tycoon, plus a thumbnail-generator side project where the prompt was tuned against real user complaints.

Contents

What makes a Roblox thumbnail click

The Discover page is a wall of small tiles. Your image is about 256 px wide next to dozens of others, and players decide in under a second. Everything below follows from that.

1. One clear subject

• One focal point, taking up roughly 40–60% of the frame. Why: a row of equal-sized characters spread evenly has no focal point and reads as noise at tile size. This was the single most common reason images were rejected.
• If the idea has a "special" character (the boss, the impostor, the max-level unit), make it obviously bigger, brighter or isolated. A special character who looks like everyone else is wasted.
• Silhouettes must not merge. Leave space around faces and around the key prop.

2. A low hero angle

• Put the camera low and looking up for power, scale and "epic". Parades, bosses, giant units and generals all read stronger from ground level.
• Use a high three-quarter angle only when the map itself is the pitch (conquest, territory, a factory floor).
• Use forced perspective when something should fly at the viewer (a ball, a missile, a crate).

3. Contrast, not detail

• Make the subject brighter or more saturated than the background, never mid-tone on mid-tone.
• Use saturated Roblox colours: blue sky, green baseplate, gold rewards. Muted "realistic" outfits (denim, pastels) disappear at small size.
• Use rim light on the hero. It separates the hero from a busy background more cheaply than anything else.
• Squint test: shrink to 256 px wide and blur. If you can't tell the subject and the action apart in one second, the image fails. tools/contact_sheet.py --squint does this for a whole batch.

4. A bold, outlined title

• Use 1–4 words in white with a thick black outline, across the top, in Roblox-style heavy rounded caps. Nearly every top performer in our batches used exactly this.
• The title states the hook, not the game name: "MAX LEVEL TANK", "RAID INCOMING!", "1 TANK VS 1,000".
• A secondary price tag or badge is fine ("$1,000,000", "8/8", a countdown "0:10"). Never use more than two text elements. Why: a third one shrinks all of them below readable size.
• Text is optional. Some genres (horror, mood pieces) work better without any.

5. Show the mechanic

The best images are the game loop in one frame: a progression lineup, a before/after, a reward bursting open, a raid coming over a hill. If a player can't guess what they will do in the game, the click turns into a bounce. That hurts more than not getting the click, because Roblox measures what happens after the click too.

6. 16:9, always

• Roblox game thumbnails are 16:9 (1920×1080 is the upload target; 1376×768 or 1024×576 from generators upscales fine).
• Generate natively at 16:9. Never crop a square image down. Why: cropping cuts off the title or the subject's head, and models compose square images for a square frame. See pipelines.md: some endpoints silently return square output.
• Tell the model not to add letterbox or cinematic black bars. Why: a cover-crop can't remove them without losing the frame.

7. Rules that are not negotiable

• Fictional flags only. Every flag, banner and emblem is invented: name its colours and symbol in the prompt and add "(no real-world flags)". Why: real national flags are a moderation and audience risk in a kids' game. Models drift to real ones anyway (a red-and-white eagle flag and a row of recognisable national flags both showed up in our batch), so the checklist catches them.
• Invented landmarks only. Say "an invented domed capitol building, not a real building". Why: without that, "capitol" became the US Capitol and "victory arch" became the Arc de Triomphe.
• Roblox, never LEGO. Avatars are tall and slim, about 3× taller than wide, with a small block head and long rectangular limbs. No raised studs, no minifigure heads. Why: "blocky" alone collapses into LEGO minifigures, and so does "chunky".
• Copy no one's art. Use reference thumbnails for style (angle, lighting, title treatment, colour). Never reproduce a specific competitor composition, character or logo 1:1. Spin the idea: their "army parade" becomes your "tank column", "victory arch" or "paratrooper sky".

Workflow in one screen

1. Pick 5–10 ideas from idea-patterns.md that show your mechanic.
2. Write one request per idea (prompt-system.md) into a requests file.
3. python3 tools/build_picker.py requests.txt gives a page with "copy full prompt" buttons, so a collaborator can generate by hand too.
4. Generate with reference images attached (pipelines.md). Batch 10 at a time.
5. python3 tools/contact_sheet.py out/ --squint and review with review-checklist.md.
6. Spin variations off the winners, not off the losers. In our run the best first-round image (an endless parade, low angle, a giant fictional flag) became the template for the next 12.
7. A/B test the top 2–3 using Roblox's thumbnail experiment, with a stable title.

Examples

Our own outputs (Google Flow, Nano Banana Pro, 10 references attached), downscaled:

• examples/evolution_lineup.jpg: the "evolution lineup" pattern, with upgrade arrows between stages
• examples/cheap_vs_rich_split.jpg: the "$1 vs $1,000,000" hard split, with price tags as the secondary text
• examples/reward_crate.jpg: the "legendary crate" reward pattern, using a light beam, a loot spill and characters running in

Checklist

• One subject at 40–60% of the frame, separate from the background
• Low hero angle, unless the map is the pitch
• Title of 1–4 words, white with a black outline, spelled right
• 16:9 natively, no black bars
• Only fictional flags and invented landmarks
• Roblox proportions, not LEGO
• Passes the 256 px squint test
• Shows what the player actually does in the game