using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var list = new List<string>{"2.1-hello","2.2-world","2.3-people","2.10-everywhere", "foo"};

        list = list

            .Select(s => (String:s,Version:GetVersion(s), LastPart:GetLastPart(s)))

            .OrderBy(x => x.Version)

            .ThenBy(x => x.LastPart)

            .Select(x => x.String)

            .ToList();

        Console.WriteLine(string.Join(Environment.NewLine, list));

    }

    private static Version GetVersion(string s, string delimiter = "-")

    {

        int index = s.IndexOf(delimiter);

        if(index == -1) return null;

        return Version.TryParse(s.Remove(index), out Version v) ? v : null;

    }

​

    private static string GetLastPart(string s, string delimiter = "-")

    {

        int index = s.IndexOf(delimiter);

        if (index == -1) return s;

        return s.Substring(index + delimiter.Length);

    }

}