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Advanced Installer: Suggestions

This document describes the design of the 'Suggestions' system within Advanced Installer, pictured in the following mockup below:

There is an image here, once it's in the ADRs folder, I promise >w<

Context Statement

When using the Advanced Installer, the user should be provided with 'hints' dictating where a file might require to be placed based on a number of heuristics.

This is part of the UX effort to 'Make Modding Easy' and a general requirement of our Advanced Installer Design.

Considered Options (Suggestions)

  • Reusing the Deployment System (InstallFolderTarget) for suggestions.
  • Creating a Suggestion System from scratch.

Decision Outcome

Rather than splitting the metadata in two, we can leverage the existing InstallFolderTarget system in order to implement Advanced Installer suggestions; as that system already has required metadata.


  • [Good] Strong code reuse as InstallFolderTarget already has required metadata to support this functionality.
  • [Neutral] Each InstallFolderTarget folder will now need a description.
  • [Neutral] All games will need to be converted to new InstallFolderTarget system.
  • [Negative] The InstallFolderTarget list may not contain all folders that the user may want to drop their files manually to.

Implementation: Reuse of InstallFolderTarget

The parts of InstallFolderTarget which are usable by the suggestion system will be lifted out into a new interface, shown below:

/// <summary>
/// Represents a target used for suggestions for installing mods within the Advanced Installer.
/// </summary>
public interface IModInstallDestination
    /// <summary>
    /// GamePath to which the relative mod file paths should appended to.
    /// </summary>
    public GamePath DestinationGamePath { get; init; }

    /// <summary>
    /// List of known recognizable file extensions for direct children of the target <see cref="DestinationGamePath"/>.
    /// NOTE: Only include file extensions that are only likely to appear at this level of the folder hierarchy.
    /// </summary>
    public IEnumerable<Extension> KnownValidFileExtensions { get; init; }

    /// <summary>
    /// List of file extensions to discard when installing to this target.
    /// </summary>
    public IEnumerable<Extension> FileExtensionsToDiscard { get; init; }

Acquiring IModInstallDestination(s) During Deploy Step (a.k.a. GetModsAsync)

Extend the GameInstallation abstract class to expose a property which returns IModInstallDestination(s) for the game's most common directories. To do this, we will add an abstract method into AGame, to accompany the existing GetLocations() method.

This property is populated with the following elements:

  • All GamePath entries (i.e. Game folder, Save folder, Config folder, etc.)
  • All InstallFolderTarget entries (e.g. Data folder for Skyrim.), as IModInstallDestination.
  • Custom IModInstallDestination(s) defined on a per game basis.
  • Remove duplicates.
  • Apply the filtering steps detailed below. (Detailed in future ADR/Issue)

This interface can be accessed during the deploy step under GameInstallation structure.

Note: Currently we don't auto fetch, InstallFolderTarget(s) [as in, auto add targets with 0 code] for the following reason(s):

  • We might potentially one day have directories that GenericFolderMatchInstaller might use, but we don't want to display to user.
  • We can only pull locations from GenericFolderMatchInstaller in current code, but that lives in an inaccessible package/project from AGame.