Dynamically finds the install location of Neos through Steam and dynamically resolves references to its DLLs.

NeosLibraryLoader.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using Microsoft.Win32;

namespace NLL
{
    internal static class NeosLibraryLoader
    {
        public const string NeosSteamId = "740250";

        /// <summary>
        /// Contains the path to the root directory of the local Steam install based on the system registry.
        /// </summary>
        public static readonly string SteamInstallPath = (string)(Registry.GetValue(@"HKEY_LOCAL_MACHINE\SOFTWARE\Valve\Steam", "InstallPath", null)
            ?? Registry.GetValue(@"HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Valve\Steam", "InstallPath", null));

        /// <summary>
        /// Contains the path to the main Steam library games folder.
        /// </summary>
        public static readonly string SteamMainLibraryPath = Path.Combine(SteamInstallPath, "steamapps");

        /// <summary>
        /// Gets the path where Neos is installed through Steam.
        /// </summary>
        public static string NeosInstallPath
        {
            get
            {
                var neosManifest = "appmanifest_" + NeosSteamId + ".acf";

                var neosLibrary = SteamLibraryPaths.First(library => File.Exists(Path.Combine(library, neosManifest)));

                return Path.Combine(neosLibrary, "common", File.ReadAllLines(Path.Combine(neosLibrary, neosManifest))
                    .First(line => line.Contains("\"installdir\"", StringComparison.OrdinalIgnoreCase)).Split('"')[3]);
            }
        }

        /// <summary>
        /// Gets the paths to all existing Steam libraries.
        /// </summary>
        public static IEnumerable<string> SteamLibraryPaths
        {
            get
            {
                var libraryFile = Path.Combine(SteamMainLibraryPath, "libraryfolders.vdf");

                return File.ReadAllLines(libraryFile)
                    .Where(line => line.Contains("\"path\"", StringComparison.OrdinalIgnoreCase))
                    .Select(line => line.Split('"')[3])
                    .Select(path => Path.Combine(path, "steamapps"))
                    .Where(path => Directory.Exists(path))
                    .Append(SteamMainLibraryPath);
            }
        }

        /// <summary>
        /// Sets up an Assembly loader that checks the Neos install folder.
        /// </summary>
        public static void SetupAssemblyLoader()
        {
            AppDomain.CurrentDomain.AssemblyResolve += neosAssemblyResolver;
        }

        private static Assembly neosAssemblyResolver(object sender, ResolveEventArgs eventArgs)
        {
            if (eventArgs.Name.Contains("resources", StringComparison.OrdinalIgnoreCase))
                return null;

            var assemblyFile = eventArgs.Name.Contains(',') ?
                eventArgs.Name.Substring(0, eventArgs.Name.IndexOf(',')) : eventArgs.Name;

            assemblyFile += ".dll";

            //var targetPath = Path.Combine(NeosInstallPath, "Neos_Data", "Managed", assemblyFile);
            var targetPath = Path.Combine(NeosInstallPath, "Tools", "AdminX", assemblyFile);

            if (File.Exists(targetPath))
                return Assembly.LoadFile(targetPath);
            else
                return null;
        }
    }
}