Simplify the following text for a Grade 11 native English-speaking person.
Original: After the critical and box office failure of the previous installment Rocky V , Stallone had decided to write , direct and star in a sixth installment which would be a more appropriate climax to the series .
Simplified: After the critical and box office failure of the previous and presumed last movie Rocky V , Stallone had decided to end the series with a sixth movie which would be a more appropriate ending to the series .