Call of Duty

Token moments of horror don't change a thrilling war loop. Call of Duty 4: Modern Warfare's success set off a wave of set-piece, one-man-army military shooters. Their brief moments of reflection are described, following Matthew Thomas Payne's Playing War, as a sleight of hand that rationalises the rest of the gameplay.

"There might be some moments of reflection or horror in these games, but it could be argued that these are often simply there to rationalise the rest of the gameplay."

The killcam turns your death into a reason for revenge. Showing players who killed them makes them want to hunt that player down. Monolith cited the killcam, alongside Burnout's crashes, as an influence on Shadow of Mordor's Nemesis System.

Monolith tried to recreate that multiplayer rivalry with AI characters, making death a story beat instead of a reload.

Regenerating health and cover make the combat calmer and simpler. Modern Warfare is contrasted with DOOM: regenerating health makes players hide rather than change approach, and cover removes the question of position, leaving fewer decisions at once.

Indistinct enemies and two-weapon loadouts are listed as other conventions that flatten choices.

Modern Warfare's Protanopia filter still lets red enemy names vanish. The full-screen filter doesn't stop red enemy names from blending into the background. Full-screen filters often don't work as intended and mostly make the game look ugly.

Apex Legends' three distinct palettes with an in-menu preview are given as the better approach.

Choosing safer colour pairs helps colourblind players by default. The series has long used red and blue teams instead of red and green, and offers an option that swaps green and red labels for blue and yellow.

A single recolour won't suit everyone, so separate palettes for deuteranopia or protanopia, tritanopia and achromatopsia are recommended.

Modern Warfare 2's deathstreaks help struggling players, but sparingly. Players who die repeatedly get a deathstreak bonus, a negative feedback loop that narrows the skill gap, like Mario Kart's blue shell for players at the back.

"These are pretty contentious, and must be used sparingly."

Choosing safer colour pairs helps colourblind players by default. The series has long used red and blue teams instead of red and green, and offers an option that swaps green and red labels for blue and yellow.

A single recolour won't suit everyone, so separate palettes for deuteranopia or protanopia, tritanopia and achromatopsia are recommended.

The grenade warning has a visual cue, not just a voice bark. Call of Duty pairs its audible grenade bark with a clear visual cue, so deaf, hard of hearing or muted players still get the warning.

Overwatch's ultimate voice lines and Metal Gear Solid V's unsubtitled grenade shout are the counterexamples: "Without sound, you're completely screwed."

Black Ops dampened the killstreak runaway loop by cutting what fed it. In Modern Warfare, killstreak rewards counted toward further streaks, so a predator missile could chain into an AC-130 and then a tactical nuke. Black Ops stopped rewards from counting, so players had to earn the kills themselves.

Killstreaks are a positive feedback loop: success raises the odds of future success, compounding a winner's lead the way losing a piece does in chess.

A scripted linear mission works when each beat plays differently and intensity builds. Liberation moves from espionage to stealth, to long-range then close-range firefights, to a sniper and Molotov defence. Each beat has its own speed and direction, building from a quiet start to a bombastic finale.

Mark Brown picked it as one of 2017's best levels and called the pacing "the real star". The mission ends on a slow-motion, ears-ringing shot of a half-track blowing up. His verdict: a heavily scripted, linear set piece stage had better be as good as this one.

A shallow cover-story quiz sells the spy fantasy. The opening has French spy Rousseau walk the garrison disguised as a Nazi while officers quiz him on his cover story. A wrong answer leads either to an instant game over or to an insignificant story change.

Players can find their contact by exploring, asking around, stealing a key or picking a lock, and can free captured French citizens who help later. "It feels good to know your cover story, and answer the questions correctly."

Reusing an earlier space lets players read the final defence. The bridge Private Daniels fights across in the street assault becomes the ground he defends with a sniper rifle minutes later, so players already know where enemies will come from.

The lit-up garrison covered in swastikas works as a weenie that draws the player down the street. The fight shifts from long range on the bridge to shotgun combat inside before the defence at the top.

Getting spotted in stealth just turns into a firefight. In the courtyard you plant explosives on the north and south gates with a silenced pistol, using ground, balcony or garrison routes. If detected, the game switches to a traditional firefight.

The rescued citizens join the fight, rewarding earlier choices. Brown notes the game rolls with detection, but "we still need to figure out how to do better fail states with non-traditional gameplay."

New movement tools don't change play unless aggression is rewarded. Mark Brown played Call of Duty: Infinite Warfare cowering behind walls and boxes despite wall-running being available.

Without an incentive, players "more likely play it in the most safe and boring way possible."

Controllers favour a few repeatable verbs like shooting. Call of Duty has precise aim and fire, yet its cemetery scene can only offer a single 'hold square to pay respects' prompt.

Verbs like punch, slash, shoot, drive and jump survive thousands of repeats better than others.

The sprint reload cancel survived because it rewards timing and risk. Sprinting halfway through a reload skips the rest of the animation, but sprinting too early cancels the reload. That risk makes it feel like an advanced skill rather than an exploit.

"It speaks volumes that the developers have never removed it."

A high skill ceiling keeps multiplayer players for years. Call of Duty, like fighting games and Rocket League, stays approachable to new players while depth lets advanced players keep enjoying it for years.