 The original Combat Evolved did not support online multiplayer , but players could play multiplayer locally via split @-@ screen or System Link LAN . Anniversary adds revamped multiplayer and two @-@ player co @-@ op campaign support available both online via Xbox Live and offline locally . The game 's multiplayer mode uses Halo : Reach 's engine and features seven remakes of Combat Evolved and Halo 2 maps . Anniversary also includes a new map based on Halo 's eponymous campaign level for Firefight , a wave @-@ based survival multiplayer game type in which players and their allies fight enemy groups of scaling difficulty . Anniversary introduced artificially intelligent Firefight allies to the series . 
