At http://backbonetutorials.com/organizing-backbone-using-modules/
define([
'jquery',
'underscore',
'backbone',
'views/projects/list',
'views/users/list'
], function($, _, Backbone, Session, ProjectListView, UserListView){
Is wrong because the Session is not loaded.
Also in the same page: http://backbonetutorials.com/organizing-backbone-using-modules/
app_router.on('showProjects', function(){
should be
app_router.on('route:showProjects', function(){
see more here: http://stackoverflow.com/questions/14410242/backbone-router-doesnt-work-with-requirejs