A pixel-art brawler-platformer in two chapters with two switchable heroines: fight black-hatted thugs across the rooftops and streets of an old town on the way home from school, then fall into a wuxia cloud realm to ride a banana-cat and fight a second cast of enemies in an entirely different setting.
Dual-World Adventure (双界冒险) — the name on the game's own title screen and browser tab — is a two-chapter pixel-art brawler-platformer built with GPT-6 Astra and published through ChatGPT Sites. The post that leads here names it after Chapter 1 alone: Old Town District · Way Home from School (旧城区 · 放学路), a schoolgirl fighting black-hatted thugs down an ordinary street of shopfronts — a grocery, a laundry, a used bookstore — with double jumps and rooftop crossings. Chapter 2, Cloud Mist Secret Realm (云岚秘境), drops an entirely different scene on top: a wuxia fantasy of floating mountains and cloud seas, a white-robed heroine you can swap mid-run for a second one the game calls 月弧 (roughly "Moon Arc"), a rideable banana-cat, and frog-shaped enemies along drifting platforms. Two complete environments, two casts, one save file — which is what the title actually means once you've played both.
The author, serein (@you1873118), posted this as "another" small game made with Astra — implying at least one earlier one, though nothing else under that handle turned up in this site's own catalogue to link to. Nine hours later she followed up with a second post reading only "参考图：" (reference photo) and a picture of a real street: the same run of shopfronts, streetlamp and crossing that Chapter 1's opening block reconstructs closely, down to the shop-sign proportions. It's about as direct a photo-to-scene comparison as this collection has turned up.
Underneath the two chapters sits a small persistence layer, not just two throwaway demo scenes: a save that returns you to your most recent checkpoint, a gold shop for healing and strength potions plus two-level attack and defense badges capped per chapter, and a fastest-clear leaderboard for each chapter's own speedrun.
How to play Dual-World Adventure
- From the title screen, choose 开始第一关 (Start Chapter 1) for the Old Town District street, or 第二关 · 云岚秘境 (Chapter 2 · Cloud Mist Secret Realm) once it's unlocked; a checkpoint-resume button appears in both places once you have a save.
- On keyboard: A/D or the arrow keys move, Space is a double jump. J is a three-hit combo (hold Down and press J for an uppercut), K is a heavy strike, L dodges (press J mid-dodge for a dash attack), U and I are two further special attacks, and Up interacts with objects and NPCs. Holding Down while jumping drops you through a one-way platform.
- On touch, a joystick on the left handles movement and jumping, and buttons on the right cover every attack. The game's own controls guide says the joystick and buttons support multiple simultaneous fingers, so moving and attacking together works on a phone.
- Chapter 2 adds Q to swap between its two playable heroines and R to mount the banana-cat companion.
- Both chapters run a live timer toward a "hidden entrance" a fixed distance away — 271m in Chapter 1, 111m in Chapter 2 — and reaching it quickly is the game's own scoring hook, tracked on a fastest-clear leaderboard reachable from the pause menu.
- The 菜单 (menu) button pauses and opens an adventure menu: save and return to chapter select, open the gold shop, check the leaderboard, or resume.
Controls: A/D or the arrow keys to move, Space to double jump. J is a three-hit combo (Down+J uppercuts), K is a heavy strike, L dodges (J during a dodge is a dash attack), and U/I are special attacks, with Up to interact. Holding Down while jumping drops you through a platform. Chapter 2 adds Q to switch heroines and R to mount the banana-cat. On touch, a left-side joystick moves and holding the attack button auto-combos.
Click Fullscreen above the game for the largest play area. If the game does not load, use Open in new tab to play it directly from our copy.
Why it's worth your time
The two chapters are not a reskin of each other — they're built as two distinct environments and enemy sets. Old Town District is a grounded pixel street with realistic shopfronts and a straightforward beat-em-up brawl; Cloud Mist Secret Realm swaps in floating platforms, ladders, a pagoda roof, a rideable mount and frog-shaped enemies against a mountain-and-cloud skyline. That's a genuinely different second half, not a palette swap.
The whole game — code, sprites, every UI panel — ships as one self-contained HTML file (about 2.1MB), the same pattern this site has already mirrored several times from ChatGPT Sites/Astra builds (Infinite Garden, Melon Lab, Mosswing among them). It runs fully offline once loaded, which is why the mirror below is a single-file capture with nothing else to fetch.
The gold economy is capped, not infinite: potions don't stack, and the two purchasable badges (attack and defense) top out at level 2 each per chapter, so buying your way to power has a real ceiling.
The tweet that leads here names the game after Chapter 1 alone (旧城区 · 放学路); the game's own title screen leads with 双界冒险 (Dual-World Adventure) instead, a name that only makes sense once Chapter 2 exists. This page uses both — the in-game name up front, the post's own name as the subtitle — because they're naming two different scopes of the same project at two different points in its life.
How it was made and where it lives
Published through ChatGPT Sites (chatgpt.site) — the same hosting pipeline GPT-6 Astra uses to ship playable games straight from a prompt. The author publishes as sgyno09. Original: https://old-town-serein.sgyno09.chatgpt.site/. The Play button above runs our own unmodified copy, so the game keeps working here if that page goes down — which on free hosting usually has nothing to do with the author. Nothing about the game itself is changed, and the original stays linked from every page.
ChatGPT Sites is the hosting side of the workflow OpenAI describes for building games with GPT-6 Astra: the model writes the game, then publishes it to a public address in one step. That is why so many of the newest single-file browser games are appearing on chatgpt.site domains.
The post that led us here
serein@you1873118A spur-of-the-moment idea — made another small game with Astra. Old Town District, the walk home from school.
If you like Dual-World Adventure, try these
Street Kid and Underground Boxing are this site's other punch-and-dodge brawlers, with a similarly combo-heavy J/K/L control scheme, even though both were built by a different author (sonic0828, not serein) — worth trying if Chapter 1's street fight was the part you liked.
Frequently asked questions
- Is "Dual-World Adventure" the same game as "Old Town District · Way Home from School"?
- Yes. They're the author's own two names for the same project at two different points: the tweet that leads here names it after Chapter 1 alone, and the game's own title screen leads with the name that covers both chapters together.
- Does it work on mobile?
- Yes — an on-screen joystick and attack buttons appear on touch devices, and the game's own controls guide says they support multiple simultaneous fingers, verified with this site's own phone-emulation check.
- Is my progress saved?
- Yes, to a checkpoint stored in your browser. The adventure menu says equipment and gold carry over between sessions on the same device.
- What's the "hidden entrance" distance shown during a run?
- Each chapter has its own live speedrun timer toward a hidden entrance a fixed distance away (271m in Chapter 1, 111m in Chapter 2). Reaching it quickly is the closest thing the game has to a scoring goal, and times are tracked on an in-game fastest-clear leaderboard.
- Is this a fan remake of something?
- No — the game's own footer describes it as 原创关卡 (original levels), not a remake of existing characters or IP.
- Is Dual-World Adventure free to play?
- Yes. Everything on Floating Arcade is free, with no account, ads or downloads.
- Can I embed this game on my own website?
- Yes — copy the snippet below. The embedded player links back here, which is how we ask to be credited.
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