The UNSC Attack Cyclops is a 'quasi' build set, like the ODST Drop Pods of Yesteryear, which comes with a pilot, and the buildable mecha for which the set is named. The UNSC Cyclops appears only in the game Halo Wars, and despite the lack of success of that title, was a popular vehicle. It can be thought of as the Spiritual Ancestor of the more widely known Mantis from Halo 4.
From the Package:
The UNSC Attack Cyclops is a multi-role exoskeleton outfitted for special military manoeuvres (it pays to remember that Mega Brands is a Canada based company) deep behind enemy lines. Always ready for close ranged combat with its crushing gauntlets and devastating dual M12s, it is a powerful combat weapon that also tears Covenant superstructures and vehicles in half.
It's a pretty neat set, all told, and includes a Spec Ops colored UNSC trooper, a Cyclops, a Sniper Rifle, and two machine guns for the mech.