python – Suddenly returned value "None" in the simple recursive function

I am a Python student in the early stages of learning.

Today I learned about recursive functions and, in an attempt to prove it, I wrote the following code. The goal was to eventually activate a message by checking a Boolean return, but the return still appears as None.

I would like to add that the Boolean trigger works if the input is exactly "0".

In my eyes, the code is as simple as it can be, so I am not sure what is causing the return of any. It must be some technical detail to which I have not been exposed. Any help is appreciated.

def countdown(s):
    # Why doesn't this return True even if it prints blastoff?
    if s <= 0:
        print(s)
        print("Blastoff!")
        return True

    elif s > 0:
        print(s)
        countdown(s-1)


tMinus = int(input("Type a number: "))
if countdown(tMinus):
    print("He's gone, Jim!")