You will not regret it. Created by upstart Valve Software and published by Sierra, it is a wonderful blend of action and scripted sequences, filled with suspense and drama. Having won basically every award a game could possibly receive, it doesn't just stop at giving you one excellent game. Now bundled with the Half-Life Game of the Year edition is Team Fortress Classic, a freeware game previously accessible only by a massive download. The key to the game is the balance of the classes.
Spies can change uniforms, appearing as a member of the enemy team.
Engineers can create powerful sentry guns, which shoot any invader on sight. Each class has their own special ability which makes them useful in a team-oriented battle. The popularity of the game is such that there are always enough players and enough servers to find a decent game. Unfortunately, while playing good competition over the internet is the game's biggest draw, the reality of the internet taints a game every once in a while. People who cheat, who cry and moan, who trash-talk as if their proficiency in playing a game is actually important in life, can and will bite you on the ass every once in a while.