// Components ( ignore the formatting, this saves space )
public struct Position{ float X, Y };
public struct Velocity{ float Dx, Dy };
// BaseSystem provides several usefull methods for interacting and structuring systems
public class MovementSystem : BaseSystem<World, float>{
    private QueryDescription _desc = new QueryDescription().WithAll<Position, Velocity>();
    public MovementSystem(World world) : base(world) {}
    
    // Can be called once per frame
    public override void Update(in float deltaTime)
    {
        // Run query, can also run multiple queries inside the update
        World.Query(in _desc, (ref Position pos, ref Velocity vel) => {
            pos.X += vel.X;
            pos.Y += vel.Y;
        });  
    }
}
public class Game 
{
    public static void Main(string[] args) 
    {     
        var deltaTime = 0.05f; // This is mostly given by engines, frameworks
        
        // Create a world and a group of systems which will be controlled 
        var world = World.Create();
        var _systems = new Group<float>(
            new MovementSystem(world),   // Run in order
            new MyOtherSystem(...),
            ...
        );
      
        _systems.Initialize();                  // Inits all registered systems
        _systems.BeforeUpdate(in deltaTime);    // Calls .BeforeUpdate on all systems ( can be overriden )
        _systems.Update(in deltaTime);          // Calls .Update on all systems ( can be overriden )
        _systems.AfterUpdate(in deltaTime);     // Calls .AfterUpdate on all System ( can be overriden )
        _systems.Dispose();                     // Calls .Dispose on all systems ( can be overriden )
    }
}