Ok, here is a nice HL quiz. bits taken from HL1 and some mods.
Q1: In HL redemption what was the picture on the magazine in the armory at the start of the game?
Q2: In Blue Shift how many scientists are eating at the pizza place at the start of the game when you are on the tram?
Q3: In HL 'Office Complex' how many grunts are found throught the level?
Q4: In Op4 what where the character models of the first 2 soldiers you come across that are alive and will follow you (After the chopper crash)
Q5: How many fire door buttons can you close in the level 'We've got hostiles'
Q6: is a shotgun, revolver or MP5 next to barney in the control room in the level: 'Power Up'