Snippet to demo how to intercept the Umbraco route hijacking before a suitable controller is found

CustomRenderControllerFactory.cs

using System;
using System.Web.Routing;
using Umbraco.Web.Mvc;

public class CustomRenderControllerFactory : RenderControllerFactory
{
    // Attempt to resolve an alternative controller 
    // This methods is called for all controllers in the request pipeline including surface controllers and possibly third party controllers.
    // We need to make sure we only hijack the actual Umbraco page request.
    public override Type GetControllerType(RequestContext requestContext, string controllerName)
    {
        var routeData = requestContext.RouteData;
        if (routeData.DataTokens.ContainsKey("controller") && routeData.DataTokens["controller"].Equals("RenderMvc"))
        {
            // Add your own logic
            if(controllerName == "ThatController")
            {
                controllerName = "ThisController";
            }
        }

        return base.GetControllerType(requestContext, controllerName);
    }
}