Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
"To Hear the Tumult of Children" (20 points)	Complete the game.
3.711 m/s² != 9.780 m/s² (10 points)	Destroy a Drone using a pushable object.
A Ninja In Tweed (10 points)	Cross Hyde Park North without dying once and being spotted by a single Drone .
Follow me! (10 points)	Free all prisoners from holding pens in Martian Cylinder.
Home again, home again (10 points)	Complete Stamford Street, South Bank level.
I Am Arthur Clark (50 points)	Complete the game in one sitting without dying.
Light in the Darkness (10 points)	Complete London EC4 Underground.
Martian Exterminator (10 points)	Complete Hyde Park level.
Old School (40 points)	Complete the game without dying once.
Selfless (10 points)	Give Jenny the gasmask.
Sole Survivor (10 points)	Escape Bathurst Mews using first NPC targeted by Tripod .
Speed Demon (10 points)	Beat the Rooftops north of Bayswater Road in under 3 minutes.