Pick a Call of Duty 4 loadout, then fight the Combine in City 17 with CoD4 gunfire.
Play Half-Life 2 as a Call of Duty 4 soldier.
A loadout screen opens first: choose a primary (M4A1, AK-47, MP5, M1014), a sidearm (M1911 or USP) and your grenades. Then you deploy into City 17 with your kit, and every shot sounds like Call of Duty 4.
What you get
What you need: your own copies of Half-Life 2 and Call of Duty 4: Modern Warfare (2007). Nothing from either game is included in the download.
Notes: single player only. Weapons keep their Half-Life 2 models; only the gunfire comes from CoD4. If your loadout hasn't arrived a few seconds after you spawn, press F9. The mashup uses cheat commands to hand out your loadout.