That's the first lesson you learn in Battlefield 3's online mode, and it's ruthlessly enforced. If you've never played a Battlefield title before, the game's learning curve is more of a brick wall. Expect to spend most of your first play sessions watching the three-second "Deploy" timer count down towards zero. BF3 focuses on teamwork, even in relative free-for-alls, like Team Deathmatch. Coordinated assaults and flanking maneuvers are required when taking fortified positions. Oftentimes, the best way to assault an enemy objective is to hunker down and watch both the mini-map and the exchanges of tracer fire.
Maps like Caspian Border are huge, assaulting enemy checkpoints requires coordination between vehicles and infantry
Battlefield 3 rewards intelligent play far more than brute-force tactics. Attacking enemy forces can often be countered by circling around behind them, or by deploying as a different class. There are four classes to choose from—Assault, Engineer, Recon, and Support. Assault forces carry M16's and medkits, Recon is for snipers and spotters, Engineers are designed to destroy/repair vehicles, and the Support class carries the M249 SAW as well as ammo packs.
Earning points and completing various objectives in a given class unlocks new weapons, gear, and capabilities, which further enhances the role a given class can play. Engineers, for example, begin with an M4 Carbine and a SMAW anti-armor RPG (we're using the US weapon versions for simplicity). The first unlockable RPG variant is the FIM-92 Stinger—a portable SAM that fires a heat-seeking missile. It's useless against land vehicles, but it's perfect for picking off enemy pilots.
BF3 gives you the option to start a map playing Assault, switch to an Engineer to keep a tank rush moving forward, then to swap your standard RPG for a Stinger in order to counter enemy air strikes, provided you've unlocked the weapon. There's no penalty for switching classes mid-map—play all four character types in one game, and you'll earn credit in all four towards the various unlocks and achievements. The system rewards gamers for playing to their strengths, while simultaneously offering incentive to experiment with multiple classes.
Even if you aren't the best shot, you can earn points for repairing vehicles, dispensing ammo and med packs, spotting enemies, capturing waypoints / fulfilling objectives, and from being in a forward position (you earn 10 points for every squad member who spawns at your position). The game also rewards points for pinning down enemy troops with suppression fire, and you earn Kill Assist points equal to the amount of damage dealt in the event that you team up on an enemy.
There are nine maps and three basic game types (Conquest, Rush, and Deathmatch.) All three game styles are playable on all nine maps and all nine maps support up to 64 players. How well this works in practice depends on the map. Some, like Caspian Border, scale beautifully. Others—Seine Crossing and Operation Metro in particular—feel very crowded with 64 players. All are gorgeously detailed. One of the heralded features of the Frostbite 2 engine is its ability to model battle damage and Battlefield 3 takes advantage of it to great effect.
Buildings collapse, creating vast clouds of debris while vehicle fires pour black smoke and battle wreckage clogs roads and creates impromptu cover between battling factions. Battlefield destruction plays a tactical role in every game without allowing matches to devolve into competitions to see who can drop more buildings on the other team.
Given the game's focus on teamwork and squad-level mechanics, the complete lack of a VOIP client is a startling omission, especially when it was a noted feature of Battlefield 2. Previous Battlefield games were lauded for a design that gave squads their own channel while providing a common channel for squad leaders to cross communicate. BF3's Commo Rose can be used to communicate quick requests or basic info, but it doesn't allow for any sort of tactical guidance or issuing squad commands.
The problem with relying on Ventrilo and Teamspeak to fill the void is that they require independent configuration and manual data entry. New players without a clan or a specific server rotation can't jump into a random game if they're looking for a higher level of play, as the Battlelog doesn't track whether or not a server maintains a VOIP service (and offers no custom data field for operators to enter this information).
From the developer's perspective, VOIP is something that only a fraction of players use, so it's easy to see why DICE would focus on other features first. The flip side to this, however, is that the players who use VOIP are the most likely to become long-term dedicated community members. At the very least, Battlelog should allow servers to note whether or not they use a service like Ventrilo.