Fight in rain soaked trenches or charge over No Man’s Land to battle in the War to End All Wars. Use authentic weaponry in your fight with the enemy, call in artillery strikes to take out foes en masse, and coordinate with your team to gain the final victory on some of the most infamous battlefields of The Great War. Screaming Steel: 1914-1918, previously known as WW1: Source is a total-conversion project being developed by devoted modders for the FPS game Day of Infamy.
The British "Aldis Brothers" scope was the workhorse for British marksmen during the war. It has the same role in WW1: Source.
You can read more about this scope in the Nov 11th 2015 update!