The Lasso, also referred to as a lariat, riata, or reata (all from Spanish la reata), is a loop of rope that is designed to be thrown around a target and tighten when pulled. In Call of Juarez: Bound in Blood, Thomas McCall uses it to climb up to viewpoints to view the area from above, and to reach objectives Ray cannot.
Mechanics
A lariat is made from stiff rope so that the noose stays open when the lasso is thrown. It also allows the cowboy to easily open up the noose from horseback to release the cattle because the rope is stiff enough to be pushed a little. A high quality lasso is weighted for better handling. The lariat has a small reinforced loop at one end, called a honda or hondo, through which the rope passes to form a loop. The honda can be formed by a honda knot (or another loop knot), an eye splice, a seizing, rawhide, or a metal ring. The other end is sometimes tied simply in a small, tight, overhand knot to prevent fraying. Most modern lariats are made of stiff nylon or polyester rope, usually about 5/16" or 3/8" in diameter and in lengths of 28', 30', 35' for arena-style roping and anywhere from 45' to 70' for Californio-style roping. The reata is made of braided (or less commonly, twisted) rawhide and is made in lengths from 50' to over 100'. Mexican maguey (agave) and cotton ropes are also used in the longer lengths.
Call of Juarez: Bound in Blood
Thomas finds a lasso in Episode II below a tree he and Ray used to climb as children, and carries it with him for the rest of the game.