I have tricks to create idea for yourself.
1. If you think about 'rewind' in normal game level it is just like replay button. You have to start game at mid of your story. If your game is escape from police. Start it with police has already captured you. And give them tasks to complete which will take them back at time when they wasn't captured.
2. This theme is nothing without basic storyline or timeline which will be controlled. You have to create story. Like above I created story of being captured by police and allowed to manipulate time by completing tasks.
3. There are currently like 9000+ participants to make your game unique and stand up against 5000+ games, don't focus on graphics but on your gameplay. If your theme is unique you can make it stand up against many. BUT, that doesn't mean completely ignore graphics keep them simple not much complex.
Hope you liked my ideas and they did they help you ?