When I see the Halo series, for 360 the flop is Halo Combat Evolved Anniversary:
http://www.vgchartz.com/gamedb/?name=halo
it first week in USA is 489k:
http://www.vgchartz.com/game/51759/halo-combat-evolved-anniversary/USA/
USA Preorder was 396k:
http://www.vgchartz.com/preorders/40860/USA/
Now back in 2014, MCC preorders is only 70k at 6 weeks from launch:
http://www.vgchartz.com/preorders/41917/USA/
Will Halo MCC be the biggest flop? probably