No-Casualties Run

Just this once, nobody dies!

Everybody Lives as a Self-Imposed Challenge. This is where you try to make sure there are absolutely minimized, if any, casualties.

Different from a No Death Run in that games where this challenge is invoked have the Player controlling multiple characters at the same time, and not with the same degree of control as in a Platformer or a First-Person Shooter. Usually invoked in RPGs and Strategy games. As the aforementioned reduced degree of control makes a No Damage Run technically impossible, this becomes the Closest Thing We Got

This may extend to enemies for a Pacifist Run.

Examples of No-Casualties Run include:

Fire Emblem, thanks to Final Death.
Pikmin: Sometimes it's not just for bragging rights, but because some players can't bear to let any of the titular adorable alien critters die.
Nintendo Wars, particularly Battalion Wars but it can apply somewhat to the turn-based games themselves.
Some players of Pokémon will regard the virtual monsters humanely and attempt to keep them from fainting at all costs. After the first generation this is rewarded by increasing your Pokemon's friendship with you (or at least letting it level up; letting it faint will prevent it from gaining experience) which affects the power of its Return move if it's learned it, and in some cases allows it to evolve into a more powerful form.
- Also, some NPCs will let you know your Pokémon's feelings towards you depending on how you treated them. Some will even give you rewards for keeping your friends well.
- There's also the Nuzlocke Challenge, in which the player is punished greatly if any of his party members ever faints.
In Return to Castle Wolfenstein, killing any civilians during the course of the game will result in a Nonstandard Game Over. It's quite easy to avoid killing them, however, unless you have a hair trigger.
Metroid Prime 3 has you run a gauntlet of Space Pirates, with marines to protect. If they all survive you get an extra reward.
Trivially easy to do in Final Fantasy Tactics, since you have three turns to save your allies from being Lost Forever.
Lemmings, where you can try to save 100% every level - even when you only need 5%
- A select few levels (exactly how many depends on which version you're playing) are impossible to save 100% on.
- Lemmings 2: Tribes, is built on the idea of saving your lemmings, as you only get as many as you saved. Only the classic tribe requires you to lose any lemmings, meaning this is almost possible.
Overlord II sort-of has this as the 'Domination' run-through, where you have to completely enslave a pair of cities... if you accidentally kill even a SINGLE citizen, you cannot achieve 100% Domination.
- Everyone else? Kill. Them. ALL.
- A better example in both games is trying to keep all your minions alive. Considering their status as highly expendable Player Mooks, this is harder than it sounds.
The point of the Hero equivalent to Chaos Runs in City of Heroes. Surprisingly, this can sometimes end up being necessary for villains.
- Also, you can set task forces and flashback arcs to attempt a no-casualties run. Having a team member be defeated will not cause it to fail, but succeeding at some of the harder ones with the "no defeats" and "no temporary powers" restrictions in place will earn you and your teammates "Master of X Task Force" badges.
Knights in The Nightmare can attract this. Same with 100% recruitment.
- The two pretty much have to go together—every time your undead allies use their weapons, they come a little closer to fading from existence, and the standard solution is to sacrifice one ally to rejuvenate another. The alternative is to have a constant stream of new recruits and leave the old ones just barely clinging to existence.
Some of the more recent Sonic the Hedgehog games have missions such as "Don't injure the townspeople," and "Don't break anything."
Dungeons & Dragons: Dragonshard, a real-time strategy game, accounted for this by giving you a "good commander" bonus for minimal casualties in a mission.
Dead Rising. There's an achievement; "Saint", for those who save almost all of the characters. To get the maximum number of survivors, you have to ignore most of the plot, to avoid Plotline Death. But you can follow the plot and still get just enough for the achievement.
Theoretically possible in X-COM, although considering the ridiculously high early-game (and mid-game, and end-game) casualty rate, this is extraordinarily difficult even on Beginner, and flat-out impossible on any difficulty at or above Normal, unless you're willing to do a lot of Save Scumming.
Metal Gear Solid allows you do this with enemies by using non-lethal weapon and even awards you for doing so, requiring you to do so to get the highest rank possible. It's possible to play through The Twin Snakes, 2, 3 and 4 with only a single kill throughout the whole saga: The Boss.
Metal Slug invites this of players, since rescued prisoners are wiped from the record when you lose a life. This is extremely hard to do, but videos exist of this being achieved in several of the games. By general agreement, Metal Slugs are not counted as casualities if they get blown up.
This is a recognised challenge in the Oddworld games, where rescuing absolutely everyone usually nets you the best ending possible. Also, KILLING everyone gets you an extra-bad ending. In the first 3 games, this means saving all your fellow Mudokens/Fuzzles. In Strangers Wrath, this means capturing all the bosses alive, and not killing any enemies that you don't have to. The only reward is extra money, or, later in the game, extra ammo.
In the Hunt gives the player a special ending if the game is completed in one credit... Your submarine is shown in the wreckage of the enemy submarines, all destroyed along with the enemy base.
The Halo series allows for this, but because of the general squishiness of your Marine allies (and later Elite and Grunt buddies) it can get very hard. To add to this, some levels allow you to pick up a steady supply of reinforcements who build up and fight alongside you, moving with you through the levels, giving you a very visible reminder of both how well you're doing and all of your failures.
One achievement in Mass Effect 2 is for keeping everyone alive during the final mission.
- There are several missions in the original, including Feros, one of the main story missions, that give you more paragon points depending on how many civilians are alive at the end of the mission.
Dawn of War 2 rewards you with extra experience and compaign points for keeping your squad leaders from being incapacitated. Their retinues, though? Meh, it's Warhammer 40K, what'd you expect?
World of Warcraft had achievements to get your raid through Naxxramas and kill all the bosses with no one hitting 0 Hit Points. If even one raid member died, the challenge could only be taken up again the next week after the reset because the casualty would be recorded.
You wouldn't expect this in a strategy game, but Heroes of Might and Magic IV has one faction, Order, that can reasonably pull this off (at least in terms of protecting itself) by recruiting entirely ranged and spellcasting units and cutting down everything before it gets close. A certain amount of attrition is expected, so by avoiding that attrition one can make one's army unreasonably powerful, killing any enemy stack in a single attack. (Nature can do this too, but it's a lot harder, and Death in particular is completely incapable of it, since the player is expected to simply replenish the losses through reviving both sides' dead.)
The main Zone of the Enders games feature missions where the player is supposed to protect buildings with civilians and/or allied soldiers in obsolete mecha. One particular battle in the second game involves trying to protect 20 of these suits while fighting hundreds of enemies across a large battlefield. The only way for the main character to feel good about the outcome is to save every single one of them.
The RTS game Blitzkrieg inspires this for the player's core units, which are selectable tanks & artillery that gain veterancy and accompany the player as he progresses through the game.
Shadowrun on the SNES offers a completely pointless challenge: The two women runners the player can encounter also happen to be the only runners with any relevance to the plot, and may be made into permanent party members. The challenge then becomes to keep both of their squishy spellcaster asses alive for the rest of the game.
In The Lord of the Rings Online, the Tier 2 Challenge for Saruman's fight involves defeating him without anyone reaching zero morale, and within 30 minutes, or else everyone instantly dies.
In the Tactics Ogre PSP remake, the title "Concord King Unbloodied" is awarded to players who avoid ever losing an ally in battle, though in Tactics Ogre it's even easier than in Final Fantasy Tactics, as the player not only has a three-count until Final Death, but reviving downed party members is also much easier (since the "item" command is automatically equipped and doesn't have to be leveled up to use a revive item) and the player can always opt to rewind time by as many as fifty turns if they discover that they won't be able to save a party member in time.