My take on an entity system framework in C#.

TinkerWorX.EntitySystemFramework.cs

using System;
using System.Collections.Generic;

namespace TinkerWorX.EntitySystemFramework
{
    public sealed class Entity
    {
        private readonly Dictionary<Type, IComponent> components = new Dictionary<Type, IComponent>();

        public void Add(IComponent component)
        {
            if (component == null) throw new ArgumentNullException("component");

            this.components.Add(component.GetType(), component);
        }

        public void Add(IEnumerable<IComponent> components)
        {
            if (components == null) throw new ArgumentNullException("components");

            foreach (var component in components)
            {
                this.Add(component);
            }
        }

        public void Add(params IComponent[] components)
        {
            if (components == null) throw new ArgumentNullException("components");

            foreach (var component in components)
            {
                this.Add(component);
            }
        }

        public T Get<T>() where T : IComponent
        {
            return (T)this.components[typeof(T)];
        }

        public void Remove<T>() where T : IComponent
        {
            this.components.Remove(typeof(T));
        }

        public Boolean TryAdd(IComponent component)
        {
            if (this.components.ContainsKey(component.GetType()))
                return false;
            this.components.Add(component.GetType(), component);
            return true;
        }

        public Boolean TryGet<T>(out T component) where T : IComponent
        {
            IComponent componentBase;
            var result = this.components.TryGetValue(typeof(T), out componentBase);
            component = (T)componentBase;
            return result;
        }

        public Boolean TryRemove<T>(out T component) where T : IComponent
        {
            IComponent componentBase;
            var result = this.components.TryGetValue(typeof(T), out componentBase);
            this.components.Remove(typeof(T));
            component = (T)componentBase;
            return result;
        }

        public Boolean TryRemoveAll(out IEnumerable<IComponent> components)
        {
            components = new HashSet<IComponent>(this.components.Values);
            this.components.Clear();

            return true;
        }
    }

    public interface IComponent
    {
        void Reset();
    }
}