The Call of Duty franchise enters the modern era with Call of Duty 4. While its presentation cannot come anywhere close to the console versions, Call of Duty 4: Modern Warfare on Nintendo DS features competent graphics with an unexpectedly smooth frame rate. Call of Duty 4 features an intense, pre-recorded soundtrack as well as plenty of voice and weapon recordings. The game is meant to follow parallel to the console versions of the game with missions taking place in the same locales, but not following the exact footsteps of the “main" version. For example, one stage takes place on a ship. In the console version, a companion ship is boarded.

The game controls much like Metroid Prime: Hunters. The touch screen is used for aiming, though the action takes place on the top screen. The touch screen also features a map, which changes in type along with the type of mission. Weapons can be selected from the touch screen, and other context-sensitive options appear there. Players move using the D-pad or face buttons, shoot with the triggers, and perform other moves using a double-tap design. Double tapping up causes players to run, double tapping down lets players crouch, and double tapping the touch screen brings up a zoomed-in gun view. The game also includes many control customization options such as sensitivity, handedness, and inversion.

The game features three difficulty settings, and the harder difficulties live up to their name. It also includes several stages, some directly based on real locations, such as Mogadishu, and some more generic, such as a bunker. There are several environments, including a boat, military bases, and various aircraft flyovers and flybys.

While the entire game is first-person shooter-based, only about 60% of the game’s twelve stages are on foot. The remainder of the game involves on-rail stages. The on-rails stages are particularly fun, since they remove the need to handle movement, and players can focus strictly on targeting enemies. In these levels, enemies appear on the ground, in buildings, and in vehicles, and they must be disposed of before they have a chance to do the same to you or your comrades. That is, the game is more than point and shoot; strategy is necessary in order to protect others as well as yourself. One of the on-rails stages includes a nighttime attack ride in a night-vision equipped plane at a high altitude. Here you have a selection of armaments, such as bombs. After some time waiting for gravity to do its work, an explosion will show up on the screen, hopefully obliterating the intended targets.

Call of Duty 4 also throws in a few touch-based mini-games. In certain levels, players will come across bombs that need to be defused or doors that must be unlocked. These games involve touch-sensitive tasks similar to the lock picking mini-games found in Spider-Man: Friend or Foe. In the bomb defusing task, players will have limited time to trace wires to their proper locations. Breaking through doors involves “hacking" the security by rotating tiles to create connected paths. While attempting the task, you essentially leave the FPS portion of the game so that you won’t have to worry about being shot in the back. It's less realistic, sure, but more reasonable given the format.

The game features local multiplayer with four game modes: death match, team death match, hunter/prey (three on one with the killer becoming the next prey), and capture the flag. Up to four players can play, and two of the maps can be played with a single card, while the others require multiple cards.

Call of Duty 4 fits an impressive array of gameplay into a platform not well known for its FPS capabilities.