From the Introduction to the Core Rules:
Why is this Game so Great?
This game is responsive rather than reactive. In most games the GM will say, "Ten ninjas burst from the shadows and attack you, roll for initiative."
In Challenger the GM will always say, "Ten ninjas burst from the shadows, swords gleaming. What do you do?" It's in the rules.
Several key factors lend themselves to this creative, player-driven approach: Initiative cannot be won by the enemy, the players always act first even when surprised (just at a statistical disadvantage), the core mechanic uses 1d20 to resolve all actions and the GM is not allowed to roll any dice (loses none of the flavour or intensity of combat but puts the ball decidedly in the PC's court), and the PC's powers let them dictate how the game will be played, whereas the skills they have allow them to help shape and mould the world the GM has created.
And, yes, 'flavour' is spelt with a 'u' if you're a Canadian.
The game's responsiveness even extends to character creation. There are hundreds of build options with dozens of races and classes to pick, choose, and combine in order to create your dream character.
And, lastly, the GM is encouraged to tailor the game to the players. If they skip the adventure, create a new one on the fly. Try to create adventures the players want to play rather than force them to play the ones you've chosen without their input.
Remember: Create and respond, don't attack and force them to react; and you’ll do fine. (I'm sorry that last bit doesn't rhyme).
What this does is let the players dictate how the game will be played. A combat can never be forced on them. They always choose how to respond to any threat, however dire. You might be surprised at how your players react when you do this. Sometimes the players will choose to talk, rather than fight, their way out of a situation just given the chance to decide on their own.
Who knows? They may even decide to use skills, do something unexpected, or attack when you thought they should roll diplomacy. That's the beauty of this game system. Enjoy.