Destroy the first sentry without taking any damage in Chapter 2: Freedom

Find the first of 61 news pickups

Finish the single player campaign on any difficulty

Locate Jacob Hargreave

Complete the evacuation at Times Square

Turn wheat into bread.

Attack and destroy a monster.

Reach the Hargreave-Rasch building

Infiltrate the alien hive

Use planks and sticks to make a pickaxe.

Craft a workbench with four blocks of wooden planks.

Infiltrate the CELL facility at Wall Street