ResearchA Day in Quake
Quake is the undisputed king of the pure action games. ID software has been the master of the first-person action shooter since they defined the genre with their original Catacomb 3D way back in 1991, an occult-themed predecessor to the better-known Wolfenstein 3D in 1992 (though it wasn't their first successful title; ever heard of "Commander Keen"?). Since then, they have run through the Doom and Quake series with a significant number of sequels for each. ID software has traditionally focused on a style of game where there isn't much storyline or logic to it: just fantastic action, a glorious 3D environment with surprises around every corner, and the highest-quality graphics and audio. It is intentionally mindless fun, made to rest the brain and be a feast for the senses.
It must be experienced to be believed. Typically, you start out with a simple blaster or other weak weapon in a starting room. Lights blink or glow softly, leaving shadows in the corners. Physics actually work; objects fall and bounce and bump each other just like reality, including the player. Fall too far and you die; fall less far and you suffer injury. As you explore deeper into the game you face an increasingly sophisticated population of monsterous opponents and find a progressively more-powerful series of weapons and ammo to pick up. Health packs will also be available along the way, as will a bunch of other items such as keys to open doors or power-ups to upgrade your armor, silencers for stealthy hunting, or the coveted "quad damage" shaped like the Quake logo itself, which will quadruple the damage of the wielded weapon.
The games just wouldn't be the same without secret areas. These are famous as the games themselves. A secret area may contain anything from bonus ammo to a whole secret level. They may be behind a disguised door or be activated by a hidden switch. Sometimes the prize is in plain sight while the way to get to it is hidden. Or there will be an obvious switch, but no effect in sight will be evident; you have to discover that it opens a secret door in a far-away area of the game. To make it fair, some clue is always there, but you have to look for it, as they might be very subtle. A lighter section of wall, a blinking light panel, a narrow gap in a floor tile, or even a shot-activated switch that is very boldly obvious... but hidden in the ceiling, right in a place where you'd never think to look up. The hunt for secrets lends a light intellectual challenge to the game, in a battle of wits to solve the various puzzles the game designers have left for you.
The Artificial Intelligence is always the most in-demand feature. It is bad form to have a monster simply stand there and hurl fireballs at you while it watches you shoot, though some allowance is made for easier prey at the beginning levels of the game. The most sophisticated AI in a monster will have you stalking it (or avoiding it's stalking you!) with a very elaborate strategy; you might have to shoot and take cover, or hurl a grenade around a corner to blast what you can't see. Foes can do the same to you, of course, and it's quite a chase when they are smart enough to snipe you from a distance then hide when you turn around. If you run away, they may come after you or not; not all of them are dumb enough to follow around a corner and walk right into the end of your shotgun.
First-person shooters are the closest expression of true virtual reality known to gaming, and the Quake series has done a lot to keep them cutting edge.