Complex sentence: The progression through the game is linear, not an open world sandbox, though the environments are designed to be explored; individual acts of the game are set in different areas of the sea, including caverns, deep oceanic areas, coral reefs and flooded ruins.
Split into simpler sentences: The progression through the game is linear, rather than open-world sandbox, though the environments are designed to be explored. Individual chapters of the game are set in different areas of the sea, including caverns, deep oceanic areas, coral reefs and flooded ruins.