old_contents: /**
   * adVenture's game engine
   *
   * @param story The story to play
   * @param screen The DOM element where the text must be displayed
   * @param input The DOM element where the player will type his choices
   * @param form The DOM element of the form to enter the action
   * @param scene Placeholder, the current scene to play
   * @param updateScreen Placeholder, function to update the screen with the new
   * 		scene
   * @param newSceneIndex Placeholder, index of the next scene to play
   */
  var engine=function(story,screen,input,form,scene,updateScreen,newSceneIndex,value){
  	value='value';
  	// Set the initial scene
  	scene=story._start_;
  	// define the function to update the screen with a scene description
  	updateScreen=function(){
  		screen.innerHTML+=scene.description;
  	}
  	// event to validate the user's choice
  	form.onsubmit=function(){
  		// get the chosen scene's index
  		newSceneIndex=scene.links[input[value]];
  		input[value]='';
  		input.focus();
  		if(newSceneIndex){
  			// update the current scene
  			scene=story[newSceneIndex];
  			updateScreen();
  		}
  		return false;
  	}
  
  	// initial screen update
  	updateScreen();
  };
  
new_contents: /**
   * adVenture's game engine
   *
   * @param story The story to play
   * @param screen The DOM element where the text must be displayed
   * @param input The DOM element where the player will type his choices
   * @param form The DOM element of the form to enter the action
   * @param scene Placeholder, the current scene to play
   * @param updateScreen Placeholder, function to update the screen with the new
   * 		scene
   * @param newSceneIndex Placeholder, index of the next scene to play
   */
  var engine=function(story,screen,input,form,scene,updateScreen,newSceneIndex,value){
  	value='value';
  	// Set the initial scene
  	scene=story._start_;
  	// define the function to update the screen with a scene description
  	updateScreen=function(){
  		screen.innerHTML+=scene.description;
  	}
  	// event to validate the user's choice
  	form.onsubmit=function(){
  		// get the chosen scene's index
  		newSceneIndex=scene.links[input[value]];
  		input[value]='';
  		input.focus();
  		newSceneIndex && updateScreen(scene=story[newSceneIndex]);
  		return !1;
  	}
  
  	// initial screen update
  	updateScreen();
  };
  
subject: test updated to be minimisable