The classical Stealth-Based Game paradigm is "hide and be quiet to avoid detection by the AI". Much of the classical stealth gameplay revolves around finding cover and shadows to hide in, walking slowly on noise-muffling surfaces, and memorizing guard patrol routes. If neutral, non-guard NPCs are present at all, they will be rather sparse and their main function is to summon the actual guards if they spot anything suspicious.
An alternative approach to stealth gameplay is to instead situate it in levels densely populated by neutral NPCs, allowing players to escape detection by the guards by pretending to be one of them: instead of cover and shadows, the player now has to look for groups of neutral NPCs to blend into; instead of managing the noise you make, you look for disguises and perform Artificial Atmospheric Actions (and avoid doing anything others are not doing) to make yourself inconspicuous; and rather than patrolling the level, most guards are stationary, and you must instead learn how the neutral crowds flow in order to get to wherever you have to go undetected.
Lost in a Crowd is one way to hide from pursuers, although blending-in gameplay does not necessarily involve crowds of NPCs: this trope also covers blending in with the guards themselves (e.g. by obtaining and wearing their uniform), as well as with the current environment by imitating the appearance and behavior of NPCs typically found in it, even if none are present at the moment. Also included are team-based multiplayer games where players have gameplay means of blending in with the opposing team and of detecting impostors in their own ranks.
Compare and contrast Social Deduction Game which is a multiplayer genre where players must blend in with and deceive other human players, rather than the AI.
- SpyParty: One player is a spy at an upper-class party, who must carry out different tasks (planting bugs, stealing documents, talking to other agents, etc.) while the other is a sniper who must identify the spy and kill him. The twist is that all the other NPCs milling around make it hard to identify which one is the spy, as they perform movements that look almost exactly like the spy's, so the sniper has to be very certain he doesn't pull a Murder by Mistake. It's even possible to let the AI take over the spy's movements, so the latter Wins by Doing Absolutely Nothing when the sniper shoots the wrong person.
- Inside has a level in which the player must join a line of mind-controlled zombies whose responses to commands are being tested — the player must walk, turn, and jump at the correct times to avoid alerting the guards and the very suspicious security drone that is only barely fooled and suspiciously watches you like a hawk the entire time. The guard dogs however are not fooled no matter what you do.
- Super Mario 3D World and Super Mario Maker 2 have the Goomba Hat. The hat makes Mario and the other playable characters look like a regular Goomba, causing enemies and even bosses to be passive to them. If they take damage, the hat falls off and any hostile creatures in the area will immediately aggro again.
- In The Elder Scrolls V: Skyrim, the quest "Diplomatic Immunity" requires you to infiltrate the Thalmor Embassy. You have the option to disguise yourself as one of the guards with the hooded variant of their uniform, though the effectiveness of this tactic varies by race. Orcs, Khajit, and Argonians will be spotted immediately because they look so different. Humans, Dark Elves, and Wood Elves will be alright from a distance, but will get caught if they get too close to the guards. High Elves, however, are able to freely walk about and can even order a guard away from his post with high Persuasion.
- The recurring Chameleon sorcery from the Dark Souls series lets players assume the appearance of a random object that fits in the current environment (such as a statue or a clay pot). While transformed, the player can change their equipment and slowly move around, and the AI enemies will not detect them unless they see them move. In the PvP multiplayer, the sorcery can be used to get a drop on an unobservant opponent, although savvy invaders will preemptively attack any suspiciously placed environment object.
- Invoked only for the sake of aesthetics in Divinity: Original Sin and its sequel: when a character enters stealth mode, their character model is replaced by a random, environment-appropriate object like a bush or a crate to better blend in with the level. However, this is merely an aesthetic effect, and the enemies will instantly see through the character's "disguise" if they come into their vision cones.
- Some areas are controlled by antagonistic or just secretive factions and getting caught in them causes guards to attack and tanks your Alliance Meter with that faction. This can be avoided by either sneaking past the guards, or simply by equipping an chest armor piece with the livery of the appropriate faction on De Sardet (companions don't count) to blend in. For this reason, it is generally a good idea to always keep a chest armor piece of each faction in your inventory, just in case.
- Father Petrus' first personal sidequest requires you to sneak into the off-limits basement of the San Matheus palace by procuring a set of servants' vests. Unlike in the regular gameplay, these have to be equipped on both companions, as well, in order to proceed.
- Planescape: Torment: In the Mortuary, you can avoid the guards by either having an NPC disguise you as a zombie (she thinks you are one and tries to "fix you up") or by murdering a Dustman and stealing his robes. Either way, Dustman guards will ignore you as long as you don't run.
- In the original Castle Wolfenstein (1981), your character can either steal a German uniform or find one in a chest. Once you do so, you won't be recognized as an enemy by regular guards and have a chance of escaping without further combat as long as you aren't seen by an SS guard.
- The "Possession" power lets the caster take control of and physically merge with the body of an animal or, with upgrades, of a human NPC for short while, using them as disguise to walk right past the guards. In Dishonored: Death of the Outsider, it is replaced with "Semblance", which lets Billie steal the appearance of an unconscious (but alive) person and thus blend in with hostile NPCs.
- The original Dishonored:
- One memorable level takes place at a masquerade ball, where the protagonist Corvo — a masked avenger — can blend in naturally as soon as he (classically) sneaks past the outside guards. Many attendees comment on how bold it is of someone to wear a mask resembling that of a wanted murderer — but are too arrogant to realize that said wanted murderer is right in front of them.
- Another level in the DLC lets Daud procure a face-concealing Overseer uniform for his infiltration of the Coldridge Prison, which effectively lets him waltz right through the first few guard checkpoints unopposed.
- The Hitman series is a poster-boy example for this trope, as it's famous for this kind of gameplay. As the title assassin, Agent 47 must navigate often large groups of unsuspecting strangers to get to his marks and kill them, all without anyone knowing he was ever there. On the way, he uses a wide arsenal of disguises to make that happen, everything from a high-security guard down to the humble mailman. Stealth Grass was introduced in Hitman: Absolution so players could hide from guards in tall grass (which later returned in Hitman 2), while Hitman (2016) added in "blend in" activities, which lets you do a mundane action related to the disguise (such as wiping a table down as a waiter in a cafe) and eavesdrop on an NPC, and not arouse suspicion. Hitman 2 also adds Crowd Blending, which lets 47 pass enforcers (or escape them) by blending into a crowd of people (as demonstrated by the image on this page).
- Thief: The Dark Project is one of the classic examples of the "skulk in the shadows and stay quiet" stealth games, but even it dabbles in blending stealth for one mission. In this mission, Garret has acquired the garb of a novice in the Order of the Hammer and uses it to infiltrate one of their secured temples. As novices take an oath of silence, no one there will ask him to speak and provided he isn't caught anywhere he isn't supposed to be, no one will challenge his presence. The challenge lies in stealing right out from under the Hammerite's noses.
- The Assassin's Creed series mixes up the classical avoid-all-contact stealth paradigm with elements of blending-in stealth, e.g. by allowing their protagonists to get past the guards undetected by mixing into a group of neutral NPCs (such as wandering scholars in the first game and courtesans in the second) or to hide in their plain sight by simply sitting down on a street bench with a couple NPCs.
- In the Destroy All Humans! series, most of the stealth gameplay takes the form of space alien Crypto having an ability which allows the player to take the form of some hapless character.
- Mercenaries: In both Playground of Destruction and World in Flames, getting into a vehicle that's owned by a faction will disguise you as being part of that faction for a while, so long as you don't honk the horn or fire any weapons. However, officers will see through the disguise if you get too close.
- In [PROTOTYPE], the player has the ability to "eat" any NPC to disguise themselves as them. Later upgrades allow you to silently devour them if nobody's looking, further encouraging stealth in certain areas.
- One half of the Asymmetric Multiplayer of Watch_Dogs has that player disguised as a random civilian in another player's game. Their goal is to hack the host player while blending in.
- In We Happy Few, unlike Sally who puts on the charm to make people tolerate or like her presence and Ollie whose only real option is to just avoid people or fight, a large part of Arthur's gameplay involves wearing the right clothes in the right place, stayings out of places he doesn't belong (or rather not getting spotted in them), and not doing anything suspicious like running, fighting, stealing, etc, when in plain view of other people. As long as he looks and acts like the people around him, nobody will realize he's a Downer and he'll be left alone. Between him being such an unremarkable person and the drug-induced forgetfulness of the Wellies, he can even effectively turn invisible by sitting down and reading a newspaper.
- In Yakuza 0 there are a couple of escort missions with enemies roaming the streets looking for you, you have to move between small crowds of NPCs, blending in with them as you make your way to your destination.