ISS File

What are ISS files and how to open them

Are you having problems opening an ISS file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your ISS files.

What is an ISS file?

ISS files have multiple uses, and Inno Setup Script is one of them. Read more about the other uses further down the page.

Inno Setup Script

These files are project files used by the Inno Setup software installation tool. Developers use Inno Setup to create installation packages for their applications.

The Inno Setup Script controls how the installation is performed, like which files are to be installed, where they must be installed, which shortcuts are created, etc.

Script files are usually edited from inside the Inno Setup Compiler IDE program. From there, the developer can "compile" the script, which results in an installation package being created.

How to open ISS files

We have identified one ISS opener that is compatible with this specific type of ISS file.

Programs that open Inno Setup Script files

Last updated: August 7, 2026

All known file formats using extension .ISS

While Inno Setup Script is a popular type of ISS-file, we know of 4 different uses of the .ISS file extension. Different software may use files with the same extension for different types of data.

InstallShield Response File

Files that contain the .iss file extension are InstallShield silent response files. These files are used by the Windows InstallShield software application. InstallShield is a program used by developers to create software installation packages.

An InstallShield Response File contains input values that are input automatically on the installer screens when running a silent installation without user intervention.

ISS opener for Windows

We have identified one ISS opener that is compatible with this specific type of ISS file.

FunCom ISS Audio File

FunCom ISS Audio File is a sound file format developed by FunCom Oslo A/S and used in their late-1990s games, notably The Longest Journey, to store game audio assets such as music, sound effects, and dialogue. It allows audio developers for these games to use compressed audio (to save space on CD or disk) while retaining enough fidelity for game playback.

FunCom games generate ISS files either as standalone files or embedded inside XARC archive files. Audio designers compress the raw sound into IMA ADPCM format with a configurable sample rate, number of channels (mono for speech and SFX; stereo for music), and block size. The game engine or a compatible audio library decodes the ISS file back into PCM for playback during gameplay.

Inside each ISS file there is a textual header composed of several space-separated fields in ASCII, such as the identifier string ("IMA_ADPCM_Sound"), block size, whether stereo or mono, total output sample count, rate divisor, and data stream size. After the header, compressed IMA ADPCM audio blocks follow. In each block the first few bytes provide initial sample and index values for decoding (for mono: one pair; for stereo: one for each channel), then nibbles of compressed data in a defined order to reconstruct the audio.

The file begins with the ASCII text "IMA_ADPCM_Sound" at offset zero, which serves as its signature.

Programs that open these ISS files

We have identified one ISS opener that is compatible with this specific type of ISS file.

IMPlay Song

We know that one ISS format is IMPlay Song. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

While we have not verified the apps ourselves yet, our users have suggested seven different ISS openers which you will find listed below.

Various apps that use files with this extension

These apps are known to open certain types of ISS files. Remember, different programs may use ISS files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about ISS file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.