Hey man, just don’t give up…these challenges can teach you a lot!
If you are short of ideas here are some amongst mine I’ll not use:
the rise and fall of atlantis
the arrival of the gods
treasure of the templars
fight at the shaolin temple
anyway…just free your mind. It’s amazing how funny it is to think of spectacular things. Ideas will come and practice will make you better.
As once Feng Zhu said, if you are stuck just pick up two topics and fuse them toghether. the more contrasty, the better. like for example fishes and ammunitions. or landscape and chinese culture. Images will come to your mind…just try to put them down.