The most played online shooter Counterstrike has a follower with the Half Life 2 Engine: Counter Strike Source.
Many real weapons, all known for their reliability. The selection is a really sweet tasted weaponary.

See here the list with all weapons and their real equivalents.

• Desert Eagle: Desert Eagle
• FN-57: FN Five-Seven
• Glock 18: Glock 18
• Dual 96G Elite Berettas: M9 Beretta Pistol
• P228: SIG P228
• USP tactical: USP Elite

• P90: FN P90
• MAC10: MAC 10 Ingram
• MP5 navy: MP5 Navy
• TMP: TMP
• UMP: UMP 45

• M3 super 90: M3 Super 90
• XM1014: M4 Super 90

• AK47: AK-47
• FAMAS: FAMAS F1
• IMI Galil: Galil
• M4A1 carbine: M4 A1 Carabine
• SG-552 commando: SIG 552
• AUG: Steyr AUG

• M249-SAW: M249 SAW Minimi

• Scout: Steyr Scout
• G3/SG-1: G3 SG
• SG-550: SIG SG550
• AWM: AWM (Arctic Warfare Magnum)

• Flashbang grenade
• Smoke grenade
• High-explosive grenade