The Browsing of Isaac (Repentance+ in the Browser)

New play address (28 October 2026). The original address, tboi.online, has stopped answering since 27 October 2026: on 28 October it timed out both in Chrome on our Windows PC and from a server in Finland, and readers had reported it on the project’s GitHub on 27 October. The author has not said why. The same build still runs from the author’s own GitHub Pages address, chiikabu.github.io/the-browsing-of-isaac, which got through loading to the opening credits in desktop Chrome on 28 October. The Play link now goes there.

The project calls itself The Browsing of Isaac. Its GitHub repository was created on 6 September 2026 and was still being updated in mid-October. On 21 October 2026 the page, its boot module and its data files all loaded from tboi.online. On 28 October the GitHub Pages copy loaded its data from the jsDelivr CDN instead.

Who made it and how it works

• Ported by chiikabu, according to the README and the credit shown in the game’s own menus.
• A recompile, not a remake. The README says the Windows executable was recompiled to WebAssembly, so “every item, synergy and bug” works as on PC. Function names come from REPENTOGON, the Isaac modding project.
• Code under GPL-3.0. The licence covers only chiikabu’s own work. The README says the game’s code, assets and name, and anything recompiled from its executable, belong to Nicalis and Edmund McMillen.

Where the game data comes from

The site serves the game for you, which is why there is nothing to import. The page lists the original packed archives (afterbirth.a, afterbirthp.a, graphics.a, music.a, sfx.a, videos.a and others) and downloads them in chunks: about 740 MB in all, with the boot module. A second repository, boi-portable, holds the same payload split into chunks for a CDN, and that is where the GitHub Pages copy fetches it from, through jsDelivr.

Both repositories say you must own the game and that the project is for “personal use of a copy you already own”. The site itself never asks for your files or checks that you own Isaac. In practice it gives Nicalis’s game to anyone who opens it, without any permission that we could find.

How to play

1. Open the Play link above. It goes to the author’s GitHub Pages copy in a new tab (tboi.online is down, see above).
2. Wait for the first download. It is large, and the page shows its progress.
3. Play as on PC. Default keys from the README:

• Controller: Xbox layout, analog sticks and rumble. Player one is whichever device starts the run.
• Phone: per the author, the left thumb moves and the right thumb shoots. You tap the item bar under the room to use items, and switching tabs pauses the run. We haven’t tested it.

Mods and saves

• Mods: the game’s MODS screen has a MOD BROWSER (press B). The author says it searches a catalogue of Steam Workshop mods, Lua mods included, and restarts the game with the mod loaded.
• Saves stay in the browser you play in. The save menu exports them as .zip or .json, and EDIT FILE imports a .dat save from PC. Clearing the site’s data deletes them.

Browsers

The README lists Chrome, Edge and other Chromium browsers on desktop or Android, and says the page tells you if your browser can’t run it. If it won’t load, try Chrome with hardware acceleration on and enough free disk space for the cache.

Is it legal?

It is an unofficial fan project. The port’s own code is open source, but the site serves the commercial game’s data without any permission we could find, so Nicalis could have it taken down at any time. The official Repentance+ is sold on Steam and consoles. We check the play page every day; if it goes, this page will say so.

Unofficial. This page is written by an independent directory. It is not made by, endorsed by or affiliated with Nicalis / Edmund McMillen or chiikabu (The Browsing of Isaac (Repentance+ in the Browser)'s author). We do not host any files, and we never link to game files, ROMs or ISOs.