Simplify the following text for a Grade 3 native English-speaking person.
Original: To save the game , players entered special portals , which have appeared in every Metroid game since . Metroid II is the only game in the series to show every stage of the Metroid creature 's development cycle ; the evolution stages that they go through are : Original , Alpha , Gamma , Zeta , Omega , and Queen .
Simplified: It 's the second game in the Metroid series .