Oh, Battlefield 1942. How many times did I steal you out of my brother's disk tray? Then get punched? It was worth it.
The single player features a campaign where you play through the maps in order of historical appearance, but there is no story. There is also an instant battle mode, but the multiplayer is really the draw. Maps and guns are perfectly balanced, as well as vehicles. This was one of the first games ever to include the concept of being a regular soldier. You didn't regenerate health. A medic had to help you. Engineers had to repair your vehicle and machine gunners had to cover you.
The impact of this game is undeniable (not to mention the impact of it's successor). It was the first to get large scale combat as well as vehicles right. From obvious copies like Star Wars: Battlefront, to the Modern Warfare series, there's always a link to Battlefield 1942.
You realize that this is a fairly short review. This is because I have nothing else to say. No story to analyze, not much else either. All I can say is, get this damn game. It's like 8 bucks at any store. Even if it was a hundred it would be worth it. The game alone is not all that you get, though, as you can now get the TENS OF THOUSANDS of mods available. From small ones that improve gameplay or add new skins, to different vehicles, or full on mods like Eve of Destruction (Vietnam maps, and vehicles, including helicopters, new weapons) or the famous Desert Combat (Middle East maps, tons of new vehicles, weapons) that influenced the production of Battlefield 2. There are also two expansion packs for the game that add maps and vehicles with new weapons.
The value, gameplay, and sheer fun of Battlefield 1942 make it a must own for anyone. Just freakin' buy it.