As an adequate shooter of it's time, halo is a classic that's worth appreciating and playing, again and again.
I personally had played the game with a friend on his Xbox, but this was before I was a hardcore gamer. When I got an Xbox 360 with Xbox Live, almost immediately I downloaded the game to have my own version, and it's worth the fifteen dollars. But enough of nostalgia, time for the real deal.
From the very beginning I was enjoying myself when playing Halo. The first level starts conveniently simple, and is easy to play and get used to the controls. Even the introduction of vehicular use aloud things to not start too quickly for me to not be used to the controls, nor too slowly to get bored of it. Gameplay throughout the entire game is very open to plenty of tactics, and that's saying something for shooter back then. Experimentation with different approaches is fun and can be rewarding, while your enemies have plenty of weapons you can take to use. Because you can use any given weapon or grenade, you'll never find yourself completely empty of weapon choices.
Enemy and fellow AI are very intelligent and are able to think on their feet. They know how to run from grenades, they use cover and scatter to maximize efficiency, and they say some pretty cool and various phrases to go with the battle. I found allies as a very important asset much of the time, so I ended up helping them as much as they helped me. Enemies aren't too diverse in species, but their tactics are never always the same while they come in different patterns.
The sound effects of bullets and explosions are just at the right volume; not too loud that I have to lower the volume, but not to quiet that I can't hear enemy chatter. The soundtrack is diverse and enjoyable to go with the battles, and never feels out of place of what I'm doing. The graphics, on the other hand, are also enjoyable to view and actually blend with the gameplay. While some environments are repeated, the possibilities of how combat can change and the use of tactics makes it almost impossible to care.
While a lot of these features seem pretty typical by todays gaming standards, at the time of halo's release, much of this was unheard in games other than in juggernauts like Golden Eye and Half Life. If the Gamespot Staff had chosen the game of the year for 2001 again, Halo should have been the winner. It did not matter if Tony Hawk 3 got a perfect 10; it, or any any other game that year, could've made such an impact in gaming like Halo did. Graphics, Music, Gameplay, Combat; Halo dominated on all fronts back then, and is still a blast even today. It defines the Microsoft way of gaming, defined the FPS, and defines some of the ideas that make a game live on forever.