I didn’t know either, so I searched.

Stolen off Reddit, two years old, so probably not AI:

FPS design changed drastically after the end of the 90’s with the rise of console gaming, more mainstream appeal, and military stuff being in vogue. Shooters started to become more realistic, grounded, slower paced, more focused on cinematics, accessible.

Boomer shooters don’t have a strict agreed upon definition, and not all these traits are required for a game to be one, but what sets them apart:

• Fast movement speed. And as that relates to combat, more focus on dodging projectiles / evading melee and less focus on just constantly taking cover from hitscan enemies.

• Player is more durable, does not go down in a fight instantly from stepping out of cover. Generally more on-screen enemies at once.

• Accurate hipfire shooting, no need to Aim Down Sights.

• No need to reload weapons, constant shooting.

• Emphasis on action, very minimal in story.

• Intricate, non-linear level design full of secrets that benefit the player.

• An emphasis on on-map item pickups (ammo, health, armor, powerups) to manage resources.

• Carry your entire arsenal of weapons at once, each bound to a specific number key instead of the two-weapon limit most modern shooters have.

• Wide variety of weapons and enemy types, weapons generally pretty creative and exotic over just standard military archetypes. Enemies very varied in health, capabilities, function instead of just being infantry.

• Generally more fantastical settings and more abstract level design. Fighting demons, aliens, eldritch beings, cultists, robots, etc. instead of just being generic military games.

Most modern shooters are completely lacking in ALL of those traits (ex. Call of Duty ) or only have about half of them (ex. Halo).