How is Nightmare Difficulty Different in Orcs Must Die

It has been published a mini-guide called "Mastering The Leaderboards" on devs blog.

In an effort to help those high-score-chasing War Mages out there, I sat down with one of our programmers to pull out information about exactly how your performance affects your leaderboard score in Orcs Must Die! Here's a look at exactly how many points you get for your various murder methods in the game. Here's a handy graph of how everything you do in the game affects your final score:

• Combat Kill 50pts
• Trap/Guardian Kill 100pts
• Rift Points remaining 100pts x Rift Point.
• Combo x3 200pts
• Combo x4 400pts
• Combo x5 800pts
• Combo x6 1,600pts
• Combo x7 3,200pts
• Combo x8 6,400pts
• Combo x9 12,800pts
• Combo x10 25,600pts
• Combo x11 51,200pts
• Combo x12 102,400pts
• Combo x13 204,800pts (by Radiokenny Jan 19, 2012)
• Combo x14 409,600pts (by Radiokenny Feb 5, 2012)
• Bonus: All Rift points remaining 10000pts
• Bonus: >= 75% Rift points remaining 5000pts
• Bonus: >= 50% Rift points remaining 2500pts
• Time: Subtracts/Adds 1 point per second over/under par time.

In addition once you get to Nightmare, the points for Combat and Trap/Guardian kills double.

There's no real benefit of headshots game play-wise, other than killing the enemies faster.

However, if you're looking to get a decent high score racked up, the headshots can be usable in a few ways:

• Keeping the killstreak going between traps.
• Getting a higher combo multiplier.

Note: Both of these points can be done without headshots, thus making it a lot harder. However, it does also require a lot of skill, to hit the headshots at the exact time you need to.