Counter-Strike 1.6 + Condition Zero

Counter-Strike is a first-person shooter video game developed by Valve Corporation. It was initially developed and released as a Half-Life modification by Minh "Gooseman" Le and Jess "Cliffe" Cliffe in 1999, before Le and Cliffe were hired and the game's intellectual property acquired. Counter-Strike was first released by Valve on the Microsoft Windows platform in 2000. The game later spawned a franchise, and is the first installment in the Counter-Strike series. Several remakes and Ports of Counter-Strike have been released on the Xbox console, as well as OS X and Linux.

Key features:

Set in various locations around the globe, players assume the roles of members of combating teams that include counter-terrorists and terrorists. During each independent match, the two teams of five players are tasked with defeating the other by the means of either achieving the map's objectives, or else killing the enemy combatants. Each player may customize their arsenal of weapons and accessories at the beginning of every match, with the currency earned through each map reset, killing other players and achieving objectives.