Exponential Potential

Ah, you just opened up your newest game and have been Easing Into the Adventure. Maybe there's some Elemental Rock-Paper-Scissors, or Standard Status Effects, but you can handle that. Then you get a new spell!

And another.

And another.

A few levels later, you are the Squishy Wizard equivalent of MacGyver and have a spell for every situation, effect or possibility. Or a weapon, or a tool, or a shiny rock made from lifeforce. One of the reasons for Linear Warriors, Quadratic Wizards.

Cousin to Crippling Overspecialization, in a nutshell this trope refers to any video game or possibly other setting where as you level up, your pool of actions and spells increases more and more, until you have a spell for literally everything and lose sight of the actual good choices, or are simply screwed over by the AI enemies using obscure or unexpected ones. Most common in games that allow you to create your own spells, whether by scribbling runes in a different order or by making your own.

Live Action TV

 * Kamen Rider flirted with this for a few years. The Heisei Riders are often Swiss Army Heroes with Multiform Balance, but Kamen Rider Decade could Power Copying and take on any of their forms, plus his own Super Mode. After him, Kamen Rider Double could mix-and-match his powers, two slots by three options each, for nine forms plus some Super Modes. Then Kamen Rider OOO had three slots by five options each for 125 forms, before his own Super Mode and additional promotional powersets. Thankfully, Kamen Rider Fourze dialed this back by giving him a large arsenal but not anything combinable.

Tabletop Games

 * In Dungeons and Dragons, Wizards can learn practically every spell in the game given enough time and gold, and can also make up their own spells, subject to GM approval. Clerics know all possible cleric spells (except those related to specific domains) automatically; druids have a slightly poorer set, but can also Shapeshift into an enormous variety of creatures. The "Erudite [Spell-to-power]" variant of the psion can learn every spell and Psychic Power in the game! (It's generally regarded as ah... slightly stronger than a standard psion). The Archivist, in a manner similar to the Wizard, can learn every Cleric spell (including the domain spells) as well as Paladin, Ranger, Druid, and Adept spells, plus certain Prestige Class spells (as well as the spells of anyone with a feat which lets them treat their spells as divine spells, which can include wizards). The Artificer can create magic items that cast spells he does not know, or convert them from casting one spell to another.
 * Ditto for Genius: The Transgression, only with super-scientific gadgets instead of magic, as well a few more limits.
 * Mage: The Ascension. There are no spell lists, only limits on what each level of each of nine main powers can roughly accomplish. There are five levels of each of the nine powers, and they can be freely mixed so long as your character believes they can be. In other words, a starting character has an unlimited number of potential effects within their power, and then it just goes up from there. Purely in theory, a character with enough abilities could turn the moon to cheese, reach up and pluck it out of the sky between their thumb and finger, pop it in their mouth, then eat it.
 * As long as skeptical muggles aren't watching.

Video Games

 * In The Elder Scrolls series, you have Fire, Ice, Lightning as damage types. You have spells to directly damage health, magic, and stamina...in two subtly-different varieties. You have levitation. Jump boosting. Buffs and debuffs for all 20-whatever skills. Demon and undead summoning. Lock opening. Telekinesis. And more. All of these effects can be custom-made based on target, duration, and area of effect, and combined as much as you want, even in impractical combinations such as "set yourself on fire for 5 seconds and heal yourself for 50 points of damage a second for five seconds". And this isn't even including spell mods.
 * Granted, setting yourself on fire for one point of damage for one second is a FAST way to raise your Destruction skill... And coupled with insta-healing that damage will boost Restoration skill... Add more stuff and you can train a whole bunch of disciplines together.
 * And then there is alchemy. Each ingredient has from 2 to 4 (mostly 4) possible effects, you can combine 2-4 of them for a potion (the potion will have any effect shared by 2 or more ingredients) which brings a huge amount of possibilities, only negated in Morrowind by being only able to use potions on yourself. Upped in Oblivion where you can create "poisons" and apply them to weapon.
 * Morrowind allowed for literal exponential potential. Try making a potion of improve alchemy, then another, then 3492348 more, buying the 1G ingredients, and occasionally selling a 394389G potion. Then make an enchanting potion, and give yourself a suit of armor that gives you virtually unlimited of every stat, renders you totally invisible, etc. Then enjoy he ending cutscene when you teleport to the final boss and one shot him.
 * Eternal Darkness: To a lesser extent, as it uses a similar system—combination—but has fewer runes.
 * The Freedom Force games offer highly customizable powers, but it doesn't reach the level of frustration described here: A single character generally only has half dozen at most.
 * In Final Fantasy Tactics, you'll end up unlocking 19 jobs.
 * In Final Fantasy Tactics A2, there are 56 jobs with hundreds of abilities spread across seven races, though some are basically just one races' slightly different version of the same job (Paladin and Defender, Soldier and Warrior, etc.)
 * Blue Mages in Final Fantasy XI. They can learn 105 spells, more than any other job, yet they can only use 20 at a time at the level cap. Bards have 68 songs, but can use them all. In fact, most of the mage jobs have a large spell list.
 * Guild Wars suffers a bit from this, as there's the same types of spell—basic poison remove, basic status recovery, etc. -- in each expansion pack. The expansion packs were also stand alone games though, so they had to make sure someone who just picked up one of the expansions and it alone still had access to some of the basic effects.
 * An interesting variant of this, which doesn't deal with magic at all, is Jagged Alliance 2. There is an overwhelming amount of different items and weapons which can be extremely useful in different situations, but it is largely impossible to carry everything you might need. Your window of opportunity for using some of these items is rather narrow as well, so a lot of items get ignored, even grenades at times, simply to avoid massive micromanagement. This becomes even more difficult with mods like JA2 v1.13 which add several hundred items to the game. The solution (as in real life) is to have specialists who carry specific items, but then they can't carry other items and may end up being useless in most situations.
 * Lost Magic: Where to start? The game gives you up to eighteen runes, which you can also combine, either in twos only or also in threes. This gives you a potential 5832 spells, out of which 400 are in the game, and the bosses and you can do everything. Terrain change, buff, debuff, shooting, summoning, nuking, tanking, capturing, walls, traps, Standard Status Effects, Roulette, etc..
 * Magicka: Essentially the main point of the game. You are given 8 different elements and can combine them up to five times to create different spells. You also choose how the power is released—casting on yourself, your weapon, the area around you, an arc in front of you, or in a blast in front of you. You get all of these by the end of the tutorial, and without mana, the only limitation is that combining certain elements (lightning and water, for example) tends to blow up in your face and how fast you can cast the spell before dying.
 * Maple Story went from four starting classes to ten, and the first five of the ten classes has at least two independent branches as it develops.
 * The current selection consists of: Ice/Lightning Wizard, Fire/Poison Wizard, Cleric, Fighter, Page, Spearman, Assassin, Bandit, Dual Blade, Hunter, Crossbowman, Gunslinger, Brawler, Thunder Breaker, Wind Breaker, Blaze Wizard, Dawn Warrior, Night Walker, Aran, Evan, Wild Hunter, and Battle Mage, with a total of 22 classes. But that's only with one advancement. If you were to count different advancements, there are well over 100.
 * The first two Paper Mario games have this, what with all those badges with effects like sleep, shrinking, multistomp... The smart way to play is to level up your badge points every level instead of your health or flower points (used for special attacks.) Because there are badges for raising your health and flowers, you'll be able to, at any time, switch from having high-health, high flower points, or whatever badges you want. It isn't hard to break the game by playing this way.
 * Pokémon. You have nearly seven hundred choices for your Mons, and nearly all of them have about a dozen or two potential attacks for their move list. And that's just from leveling up; include the attacks that can be gained from TMs and breeding and things get crazy.
 * Radiant Historia. Scrolling trough them every turn or so can get annoying sometimes.
 * Scribblenauts is like this to an extent. You have literally anything in the game's dictionary at your disposal, up to the limit on the number of objects imposed by your object bar. The player is the one who figures out new ways of doing stuff—the first time you try shooting your space shuttle or your mech with your shrink ray opens up a whole world of new solutions.
 * A surprisingly large percentage of the game's vocabulary consists of functionally identical chemicals, though.
 * The sequel plans to add adjectives to the already incredibly complicated equation.
 * This is the entire premise of Suveh Nux: Learn part of the language of magic and build sentences that do just what you want.
 * Wild Arms XF is even more confusing; there are 16 normal classes and six or seven special ones, and each of them come with four to nine unusually unique abilities. Each class and ability can be used in specific situations and often must be used strategically, meaning the game is half strategy and half puzzle.
 * Obscure PS 1 RPG Shadow Madness has this bad. Despite a level cap of 15 the game has the requisite number of spells expected of a JRPG of the era which means that characters often gain 3 or 4 per level, combined with the games awful menu not really describing what any of them do and a generally obtuse naming scheme it becomes nearly impossible to suss out what spells are actually worth using without taking notes.

Webcomics

 * Homestuck features a form of punch-card based alchemy that can be used to create and combine any object conceivable, and quite a few that aren't. Most of the protagonists have spent 10+ page montages going to town with this at least once each.