Shipping single-file HTML5 playable ads: my Unity 2022 WebGL pipeline

LUMENFORM — Sun, 04 Oct 2026 08:49:41 +0000

Last month I set out to answer a simple question: how small and how self-contained can a Unity WebGL playable ad actually be?

Three builds later, here's what I ended up with — all playable directly in the browser:

Match-3 playable (Prism Vein) — chain reactions, three special-match effects, audio end card. 4.7 MiB (EN) / 5.1 MiB (ZH)
Idle-growth playable (Core Forge) — tap-collect, three upgrade tiers, 1,000-unit milestone. ~8.2 MiB with a runtime EN/ZH switch
3D product microsite (Atlas Relay) — orbit camera, three hotspot panels, day/night toggle. 9.61 MiB

Playable here: https://www.lumenformlab.com

The constraints that shaped everything

Playable ads live inside ad network SDKs (MRAID containers), and networks impose caps: file size, single-file delivery, no external requests, muted audio until first interaction, and a CTA that fires mraid.open().

That rules out the default Unity WebGL export. The pipeline became: Unity 2022 → WebGL export → repack.

1. Export settings that matter

Brotli/gzip compression on the build payload
Strip engine code, high managed stripping level
No exceptions, no stack traces (smaller + faster startup)
IL2CPP + code stripping

2. Repack to a single file

The default export ships as index.html + Build/*.unityweb + TemplateData/*. For playable delivery this gets repacked into one inlined index.html:

base64-inline the .wasm, .data, .framework.js payloads
inline the loader
zero external requests — verifiable in DevTools: the network tab shows exactly one document request

3. Audio discipline

Network rules require muted audio until first tap. I keep an AudioContext suspended until the first pointer event, then resume it — sounds only fire after real interaction.

4. CTA through MRAID

The end-card CTA checks for mraid availability:

inside an MRAID container → mraid.open(url)
outside (plain web demo) → window.open(url) fallback

I wrapped the match-3 build in a MRAID 2.0 harness locally (getVersion() returns 2.0) to verify the bridge works.

Size results

Build	Size	Languages
Match-3	4.7 MiB	EN / ZH (two separate builds)
Idle-growth	~8.2 MiB	EN+ZH runtime switch in one build
3D microsite	9.61 MiB (18 files)	EN+ZH

Most of the match-3 savings came from texture discipline (palette-swapped sprites) and audio compression, not from hacking the engine.

What I'd tell anyone building playables

Budget the size cap first, design second
Test inside a real MRAID harness, not just a browser tab
Keep one inlined file as the single source of truth for delivery

I'm a solo developer building these end-to-end (Unity 2022 → WebGL → repack), currently taking on small fixed-scope builds. If you work with playable ads or interactive 3D, I'm happy to compare notes — all three demos are live at https://www.lumenformlab.com

DEV Community: LUMENFORM