How to play browser ports with your own files (ISO, XISO, MPQ) without losing your save

Come with me and I will tell you: many of the nicest browser ports do not include the game. They bring only new code and ask you to supply the files from the original game, which you already own. It sounds complicated, but it is quite easy, and it is exactly what keeps these projects on the right side of the law.

What “your own files” means

Each project asks for a format. Combat Lab, which runs Halo: Combat Evolved in the browser, asks for an XISO image made from your Xbox disc. Diablo ports such as DevilutionX use the DIABDAT.MPQ file from your copy of the game, whether the old CD or the version sold on GOG. Source ports of id Software games read the PAK or WAD files from your Quake or Doom installation. In every case, the game you bought is still the foundation.

Your files stay with you

Good projects state that files are processed locally, meaning inside your browser, without being sent to a server. Look for that note on the page before you pick the file. If a site asks for your file and does not say what it does with it, or offers the complete game for download without asking for anything, be careful.

How not to lose your save

Browsers keep these games’ data in the site’s storage. So here are some sweet but important tips:

• Always play in the same browser and at the same site address; switching browsers is like switching memory cards.
• Avoid private windows: everything disappears when you close the window.
• Clearing browsing data or that site’s cookies also deletes the save.
• In Safari, sites you do not visit for a few days may have their data removed; play often or export your save.
• If the project has a save export or import button, use it and keep a copy.
• Also keep a copy of your original file outside the browser.

What if I no longer have the disc?

Then the route is buying the game from official stores. Many classics are back on sale on GOG, Steam or console collections. Our guide to games ported to the browser and PC gathers free, official and open-source options, and more stories are in our Preservation section.

Source: Combat Lab and DevilutionX.