This mod comprises three distinct parts, each focusing on a different playstyle.
From the mod's full description:
The player is a Resistance agent sent to investigate the status of a previously overrun base. Upon entry, he finds lingering Combine forces that spring a trap, forcing him to blast his way back out of the base. Beach Level has three parts, each focusing on a different style of play. The first part is Reconnaissance, where the player lands on the beach and explores the area, searching for the entrance to the base. This part focuses heavily puzzles and exploration. The second part is Combat, where the player must fight his through the base. This part focuses heavily on combat. The third part is Escape, where the player must make his grand escape after successfully making his way through the base.