A tendency of video games that offer both single-player and multiplayer modes to make the latter a lot more challenging of the two. Comes in two variations:
- Strategy and shooter games (especially post-2000) are often geared towards competitive player-vs-player modes, with the campaign serving mainly as an extended Tutorial Level sequence. The campaign AI is often handicapped while the player is gradually introduced to game mechanics; the multiplayer/bot AI, on the other hand, is completely unhindered in its task of taking you down. And, of course, the human opponents are, in theory, the biggest challenge since most of them will have been playing longer than you have. Good luck dealing with the Metagame.
- Games with pronounced Co-Op Multiplayer increase the difficulty in it with the justification that more players can take on bigger challenges and stronger enemies. Some additionally impose penalties on the players to enforce teamwork, such as Crippling Overspecialization and artificial Caps. On the downside, if the game doesn't become popular, players may end up barred from most of its co-op content, unable to find enough co-players online to match the raised difficulty.
The downside of such approach is that players returning from multiplayer to single-player may find the latter boring and hardly challenging after the brutal online battles.
This trope applies specifically to games that offer distinct single-player and multiplayer modes. In Massively Multiplayer Online Games and games whose single-player mode is essentially Co-Op without co-players (in the vein of Diablo II), difficulty spikes proportional to the number of players fall under Dynamic Difficulty.
Examples of PvP difficulty spikes:
- Destiny plays this straight for balance reasons. No matter you level difference (provided you're playing in a "Level Advantage Disabled" playlist), you are just as weak as the other player. This does make it harder to master PvP, but it encourages you to get decent gear before then, then do PvP, and then get good gear as a reward.
- Fighting Games in general as players research and exploit things the computer can't. Of course the computer has some aces up its sleeve.
- In WarCraft 3, the campaign AI is quite blatantly railroaded into the same attack patterns over and over again and protected only by cheating. Online AI, on the other hand, is intended to emulate how human players will act.
- Starcraft has similar issues. In the first game the AI is fairly predictable in the campaign, but custom game computer players can be anywhere from "really dumb" to "scary effective and stupid fast".
- World in Conflict is actually a mixed example: by pitting teams of players against each other, it both gives them access to all the destructive potential only glimpsed in the campaign, and enforces Crippling Overspecialization mostly absent from the single-player.
- Pokémon battles against other players are nightmare-inducingly difficult compared to the battles against in-game NPCs. This is not only due to the absence of Artificial Stupidity, but also because Pokemon are capped at level 50, cannot switch out freely after fainting an opponent, and bag items cannot be used. And that's not counting the insane Min-Maxing and the Metagame, depending on who you battle with. In Pokemon, PvP is quite possibly the highest difficulty spike an RPG can offer.
- Minecraft can become this on servers which have PvP enabled. A fully-armed player can slaughter many of the hostile mobs easily, but mindlessly attacking other fully-armed players (especially those with potions and/or weapon enhancements) can lead to a swift and embarrassing death. It can become even more difficult if the game mode is Survival, since players might have to compete with each other for resources. The game's wiki notably has a lengthy article written on how to deal with other people, flat-out calling PvP "a hard nut to crack for many players."
- MOBA games address this issue by giving each player a score that increases with victories and decreases with defeats, matching them with people with a similar score, and matching that team with a rival team that has a similar average score. This score is best known as "Elo", due to League of Legends's use of the Elo rating system during its first few years of existence, although new systems have since been developed. New players will as a result start out losing their first game badly, but subsequent games will be easier and easier as their Elo keeps decreasing with each passing defeat, until the day their Elo is low enough to match them against opponents who are unskilled enough to be defeatable; afterwards, as the player becomes more and more skilled and starts winning more and more games, their Elo score will increase with their new victories and as a result they will be matched against increasingly more competent opponents. Likewise, if a player's skill somehow decreases, e.g. after a long hiatus or by venturing into a role they don't usually play, the player's Elo will decrease and they will be matched against increasingly unskilled opponents.
- Most MOBA games also have an extended tutorial mode that allows players to acquaint themselves with the controls, the game mechanics and their characters' strategy and usage before they come out to the matchmaking queue. Dota 2 does this with 6 tutorial levels with increasingly complex games, whereas League of Legends does this by barring new players from playing against people and forcing them to play against the AI until their accounts have reached level 5.
- Mario Kart has Rubberband AI that likes to Gang Up on the Human in single-player mode, but it still can't make a good use of items and shortcuts. Enter the online mode, where you will have your ass handed to you nearly constantly by players who pick the best driving character and kart, take advantage of all the shortcuts, and maximize chaos on the road by spamming items. Likewise, the battle modes has the AI being fairly average, but playing against others online can be quite chaotic.
- Fighting enemies in Final Fantasy XIV is generally a walk in the park due to them following a set pattern in their attacks and even savage raids and extreme primals can be conquered once you learn the patterns and what you should do. Fighting other players in the various PvP modes can be extremely daunting for people not used to it since they are fighting players who know how job skills work and the best ways to shut down players based on the jobs they're playing as. In short, a player will never fight in predictable patterns.
Examples of Co-Op difficulty spikes:
- As the trope description says, the Diablo series is mostly Dynamic Difficulty based on number of players and thus not this trope. But in the first game only, choosing to play in multiplayer mode (whether or not you actually invite any other players) resulted in increased XP requirements for leveling up, all equipment being dropped on death, and savegames saving only your character state rather than the entire world (so you couldn't leave items or gold in town between sessions). Additionally, single-player savegames were completely incompatible with multiplayer mode, and higher Difficulty Levels were multiplayer exclusive rather than New Game+ with a weird name. Later games in the series chose to increase the multiplayer focus and made most of those things standard while removing the rest entirely.
- Destiny averts this, thankfully. It's done to encourage co-op with friends and other players, to the point that doing Strikes, you are put into matchmaking to make sure you have a full Fireteam.
- Grand Theft Auto V features enemies that become much, MUCH more precise and bullet-resistant once the player goes from the solo campaign to multiplayer. It's not uncommon to knock an enemy down with gunfire, then have to fire on his or her prone body several more times just to make sure.
- The Doomsday Heist from multiplayer is a Zig Zagged Trope, as it gets more difficult the more people you have in the lobby. You can do it with 2, 3, or 4 people. While technically the enemies don't change, the fact that you have a very limited number of Video-Game Lives (if any), that they are shared for the whole team, and that random players can easily become The Load. While it's possible to organize a 4 player team of well coordinated players with synergy between them, making the missions easier than with just two, the fact that any dead weight will drag the team down means it's often easier to 2 man the Doomsday Heist with someone you know well than try to do it in a 3 or 4 people team with people you don't know too well, people who don't have voice chat capabilities, or, people you don't know who don't have voice chat.
- Many Beat Em Ups will add extra Mooks (and, rarely, bosses) when more than one person is playing.
- The Portal 2 Co-Op mode is a lot more challenging than SP, thanks to the puzzles requiring four portals to solve rather than just two.
- Mass Effect 3 multiplayer caps the player level to 20 (compared to 60 in the SP), drastically reduces available skills, and consistently pits the players against Demonic Spiders rarely encountered even on higher difficulties in SP (or not encountered at all, such as the DLC-only Collector faction). You'll end up killing more Mini-Boss enemies such as Collector Praetorians and Geth Primes in a single Gold game than in every mission of the single player of all three games combined. To put things in perspective, a generic mook during a Bronze multiplayer match (the lowest available difficulty) has about the same health and damage as an enemy in single player on Normal difficulty, while on Silver it has the same stats as single player enemies on Hard, and on Gold, has the same stats as single player enemies on Insanity. Now consider that there's also Platinum difficulty in multiplayer...
- Kingdom Hearts: 358/2 Days has the Mission Mode, which has a multi-player option. The enemies have buffed stats compared to story mode whether you have multiple players or not.
- Evil Islands doesn't allow importing your SP characters to co-op (so you have to make new ones from scratch), makes all enemies a lot tougher than in SP, and drastically reduces the XP and money rewards for quests and combat.
- When played in co-op mode, Doom games have extra enemies (including boss enemies like the Spider Mastermind and Cyberdemon) in places where they weren't there on even the hardest single-player difficulty.
- The House of the Dead series does this. Irritatingly, one boss in The House of the Dead III, The Fool, has a final attack that requires the player hitting its claw with a full clip of shots in a very short timespan (we're talking no time to reload) in single-player... and two clips in two-player, meaning that both players must fire a full clip at it and not miss. Conclusion? You're better off playing alone than with an incompetent or fooling-around player, unless you don't care about spending money.
- Par of the course for most light gun games, in fact. These games usually balance for 2 players by increasing the health/defense of boss enemies (universally designed to make players pay more quarters).
- In Brave Firefighters, playing with a second player reduces the time bonuses you can get from clearing sections.
- The Monster Hunter series has separate sets of quests for singleplayer and multiplayer. In the multiplayer quests, monsters have more health to compensate for allowing up to four players. Quests are divided into two or three distinct ranks of difficulty depending on the game, and highest rank is only available in the multiplayer quests, featuring new monsters that are unavailable in the lower ranks. Of course, a sufficiently determined player can still take on all of the multiplayer quests alone, and having a full set of four players can make a multiplayer quest go faster than its singleplayer equivalent.
- Metal Gear Solid: Peace Walker does this is Extra Ops vehicle and monster fights by adding more Mooks and making the boss itself more resistant to damage.
- PAYDAY 2 has the enemy AI come in small swarms if you're playing in single player. Playing in co-op will ramp up the amount of cops rushing you in order to provide a challenge and promote teamwork between players.
- Killing Floor 2 has the number of zeds scale with the number of players. Dosh earned and health recovered each time one heals also reduced the higher the number of players is.
- Teenage Mutant Ninja Turtles: The Arcade Game and Teenage Mutant Ninja Turtles: Turtles in Time multiply the number of enemies on screen with the increasing number of players, as well of the number of clones of the Final Boss, Shredder.
- Streets of Rage has every boss except the Final Boss come in pairs if you're playing co-op whereas playing alone only has you fighting one boss per level (Stage 6 is always a Dual Boss regardless if you're playing alone or with a buddy). Later games dropped this feature.
- In Dark Souls 1, the health of bosses increase by 50% for every phantom you summon to help you (150% health for one phantom, 200% for two), to balance out the fact that you could potentially be doing two or three times as much damage, as well as the potential tactical advantage of having multiple players. For some bosses, like O&S and the Bed of Chaos, this is a godsend, whereas it's less helpful for others, like Gaping Dragon or Manus.
- Warframe: Enemies are more numerous the bigger your squad, and bosses are higher level. That being said, due to the way health and damage scale and how different player abilities synergize, it's pretty much always better to fight in a full squad rather than alone. And that's not even mentioning that more enemies mean more rewards. A typical mission usually takes about five minutes with a full squad, but it can easily take half an hour alone.