osuIPC.cs

private static void Main(string[] args)
{
    // Find the location of the running osu! client
    string p = Process.GetProcessesByName("osu!").FirstOrDefault()?.MainModule.FileName;
    if (p == null)
        throw new Exception("Couldn't find process");

    // Load this assembly and find the InterProcessOsu class
    var ass = Assembly.LoadFrom(p);
    var ipoType = ass.ExportedTypes.First(a => a.FullName == "osu.Helpers.InterProcessOsu");

    // Create an assembly resolver, we'll need it later
    AppDomain.CurrentDomain.AssemblyResolve += (sender,  eventArgs) => eventArgs.Name.Contains("osu!") ? Assembly.LoadFrom(p) : null;

    // Get an instance of the InterProcessOsu class and get the method we need
    object ipo = Activator.GetObject(ipoType, "ipc://osu!/loader");
    var method = ipoType.GetMethod("GetBulkClientData");
    if (method == null)
        throw new Exception("Couldn't find method");

    // Invoke this method. This will require the AssemblyResolve event to return a proper Assembly where this type is located
    var data = method.Invoke(ipo, null);

    // And now pick any field and show it. There isn't much anymore, now.
    string md5 = (string)data.GetType().GetField("BeatmapChecksum").GetValue(data);
    OsuModes mode = (OsuModes)data.GetType().GetField("Mode").GetValue(data);
    var lastAction = data.GetType().GetField("LLastAction").GetValue(data);
    Console.WriteLine("MD5: " + md5);
    Console.WriteLine("Mode: " + mode);
    Console.WriteLine("Last Replay Action: " + lastAction);
    
    Console.WriteLine("Done");
    Console.ReadKey();
}

public enum OsuModes
{
    Menu,
    Edit,
    Play,
    Exit,
    SelectEdit,
    SelectPlay,
    SelectDrawings,
    Rank,
    Update,
    Busy,
    Unknown,
    Lobby,
    MatchSetup,
    SelectMulti,
    RankingVs,
    OnlineSelection,
    OptionsOffsetWizard,
    RankingTagCoop,
    RankingTeam,
    BeatmapImport,
    PackageUpdater,
    Benchmark,
    Tourney,
    Charts
}