Creating a timer in python

See Timer Objects from threading.

How about

from threading import Timer

def timeout():
    print("Game over")

# duration is in seconds
t = Timer(20 * 60, timeout)
t.start()

# wait for time completion
t.join()

Should you want pass arguments to the timeout function, you can give them in the timer constructor:

def timeout(foo, bar=None):
    print('The arguments were: foo: {}, bar: {}'.format(foo, bar))

t = Timer(20 * 60, timeout, args=['something'], kwargs={'bar': 'else'})

Or you can use functools.partial to create a bound function, or you can pass in an instance-bound method.