Online can extend a game's life, but all the best moments for me have always been single player.
Best if they're designed for single player, optional co-op usually means concessions have been made for both modes.
Only Journey has managed to enhance the experience for me through multiplayer interaction.
Second best would be Dark souls, yet at a distance already. The multiplayer and sometimes overload of spoiler messages was often breaking immersion.
Couch co-op is great for certain games, online not so much.







