''Gemcraft'' is a free-to-play TowerDefense series developed by Game in a Bottle and distributed by [[http://armorgames.com/ Armor Games]], a major source of WebGames. It has a distinct {{Fantasy}} setting with a rudimentary storyline that varies between installments.

Generally, AnAdventurerIsYou, assuming that said adventurer is always a noble [[FunctionalMagic wizard]] out to reach some goal on the other side of the world, come hell or high water. In this case, come monsters, by the bucketload. You, the SquishyWizard, must protect your tower ([[IncrediblyLamePun tower defense, get it?]]) at all costs, by placing towers next to, and traps on, the path leading to it. However, a key difference splits Gemcraft off from other tower defense games instead of being able to upgrade your traps and towers directly, you must power them with gems. Gems are mostly obtained with a spell named Craft Gem (which is basically the source of the game's name), and have distinct colors (which affect the types of powers they possess) and levels (which affect their strength). By combining gems correctly, you can create better ones to better fight those evil monsters.

The eight gem colors (and their special abilities) are:

* '''[[color:red:Red]]''': SplashDamage in the first two games. Changed to "[[KillStreak bloodbound]]" in Labyrinth: The gem gets extra power from a percentage of the monsters it kills.
* '''[[color:orange:Orange]]''': [[LifeDrain Mana Leech]]. Each time it hits a monster, you gain mana.
* '''[[color:yellow:Yellow]]''': [[CriticalHit Multiple Damage]]. The first two games gave a flat rate to deal triple damage. In Labyrinth, the multiple damage rate can be ramped up as high as you can make it (starting with double damage).
* '''Lime''': [[ChainLightning Multi-hit]]. Starts with one extra hit, but can be ramped up to be able to hit more than two monsters.
* '''Green''': StandardStatusEffects/{{Poison}}. Ignores armor, so useful for armored waves as well as swarmlings.
* '''Cyan''': [[StandardStatusEffects/{{Paralysis}} Shock]]. Can stop the monster in its tracks.
* '''Blue''': StandardStatusEffects/{{Slow}}.
* '''Purple''': [[DamageIncreasingDebuff Armor Tearing]]. In the first two games, each hit has a chance to reduce a monster's armor by a set amount; in ''Labyrinth'', each hit lowers a monster's armor by a given ratio, based on the gem's power.

The latest chapter, ''Chasing Shadows'', was released to Armor Games in April 2014 and will be released to Steam later in 2014. It removes Lime gems (moving their multi-hit to Red) and adds two more colors, changing the colors thusly:
* '''Orange''': Mana Leech.
* '''Yellow''': Multiple Damage[=/=]Critical.
* '''White''': Poolbound. Increases the gem's damage and specials when the mana pool levels up.
* '''Red''': Chain hit (from lime, and moving it closer to its original SplashDamage role).
* '''Green''': Poison.
* '''Cyan''': Regeneration suppressing: lowers monsters' health regeneration rate. (Shock was made into a Freeze spell).
* '''Black''': Bloodbound (from red). Increases the gem's damage and specials based on the number of monsters the gem has hit.
* '''Blue''': Slow.
* '''Purple''': Armor Tearing.
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!!This game series provides examples of:

* AirborneMook: Apparitions in ''Labyrinth'' just fly over the terrain, and have a lot of health. Thankfully, they don't hurt you, they're slow, they're uncommon, and they give [[MetalSlime 3 free skill points when beaten]].
** A much nastier version is the Shadow, encountered only once as a boss in the storyline, but the player can choose to fight one as a BossInMookClothing via the level settings. These can fly anywhere on the terrain, have tons of life and armor, can spawn homing shadow balls that aim for your orb, and create a large and fast swarm of Mooks. [[DesperationAttack When low on health]], the Shadow will perform TheSlowWalk right at your orb and instantly destroy it should you fail to kill the shadow.
* AllegedlyFreeGame: Gemcraft: Labyrinth and Chasing Shadows contains a five-dollar "premium" version which unlocks extra modes, skills, and battlefields.
** Chasing Shadows ups it a lot, as there are many achievements, levels, and skills that can only be found by completing certain maps in certain sectors...and those that require completing a Premium-only level are thus unaccessible.
*** The best two gems for level-grinding in Chasing Shadows, the red chain hit and the white poolbound, are premium only, thus unavailable on most maps to free users.
* AllYourPowersCombined: Crafting multi-colored gems becomes less beneficial until you combine all 8 colors into one gem. At that point, it gains the power of all 8 gem types rather than the 3 dominant ones, and its damage, range, and firing speed all skyrocket. Averted in ''Labyrinth'': Supergemming in this manner doesn't exist.
* ChainLightning: Lime gems (red gems in Chasing Shadows) can strike chain hits.
* DamageReduction: Armour level.
* DiscOneNuke: One of the early stages in Gemcraft: Labryinth has a tower surrounded by eight amplifiers. Place a gem in each of the amplifiers, and the tower gem will '''kick ass'''. This nuke becomes MUCH more powerful if the player buys the "premium" version and uses endurance mode with this strategy to get a ridiculous multiplier to their XP gained. A similar setup occurs in ''Chasing Shadows''.
** Red gems in ''Labyrinth''. They add a percentage of their kills to their damage. Meaning a red gem that's been there since the first wave can have a damage of over 1000 by the final waves. The gem won't dominate the game by itself, but becomes much more powerful when combined with the lime or yellow gems (which multiply the offensive power.)
*** This power was nerfed slightly in ''Chasing Shadows''. The black gems now multiply both damage and specials and count hits rather than kills, but use hit levels rather than raw hits.
** A different Disc One Nuke in ''Labyrinth'' (the ability to juggle monsters over mana leech traps by building and demolishing walls to keep them going back and forth over them) led to the developers putting a hard cap on the number of demolitions one could use on a level.
* FakeDifficulty: The Shadow boss from ''Labyrinth''. It has the ability to spawn a HUGE, fast ZergRush of units that will take a bit of time to take down... and there's a possibility that it spawns them ''right in front of your orb'', making it impossible to avoid massive damage.
* FlawlessVictory: Defeating a map in Labyrinth without letting any enemy touch your orb gives an xp boosting medal for that round. In ''Chasing Shadows'', the orb gives extra experience for eash flawless wave.
* GemstoneAssault: Subverted with the Gem towers that fire energy, but played straight with the Gem Bombs that you can drop on a bunch of Mooks.
* GameBreakingBug: In Labyrinth, the glitch that allows the creation of near infinite strength gems has a chance of deleting your save file.
* LevelGrinding: And lots of it. In Chapter Zero, you'll have to level up to 200 in order to max out all your stats, and in Labyrinth, there is no level cap for 3 of the skills. For the premium version, the Ritual skill will let you gain one starting and maximum mana for a set number of battle amulets you possess, based on its skill level.
* LuckBasedMission: Prior to ''Labyrinth'', crafting causes you to receive given a random-color gem based on those available in the level. The same goes for using Gem Bombs on enemy-spawning buildings -- they may or may not destroy the building due to randomized damage.
* MakeMyMonsterGrow: You can use gem bombs to provoke more enemies to attack, which also causes them to become stronger.
* {{Mana}}: This is needed to build things, craft gems, cast spells, and performs [[CastFromHitPoints double duty]] as hit points as well. It builds up slowly every second, but largely comes from monsters you kill, and gets increased by using orange gems in the right places.
* MeaningfulName: The Forgotten gets her name from the fact that she keeps escaping because she is forgotten.
* MetalSlime: Apparitions in ''Labyrinth''. They uncommon foes [[AirborneMook fly over terrain]] slowly and have a TON of hit points, but they can't harm you at all and will just enter and exit the map. However, killing these gives the player '''3 free skill points'''!
* MultiMookMelee: Because it's tower defense.
* NamesToRunAwayFromReallyFast / NamesToRunAwayFrom/TheAdjectiveOne: The Forgotten. Also, epic bosses in the first game.
* NiceJobBreakingItHero: In Chapter 0, you spend the game searching for the Gem of Eternity. When you find it and capture it, [[spoiler:it turns out to have been containing a monster (for eternity, hence the name) which then possesses you, setting the stage for the first game.]]
* OneHitKill: In ''Labyrinth'', the Shadow will perform TheSlowWalk towards your orb as a DesperationAttack. If it touches your orb before you destroy it, your lose instantly regardless of Mana left. In ''Chasing Shadows'', this ability is given to Spires.
* RewardingVandalism: Using Gem Bombs on the buildings strewn about may let you uncover hidden relics.
* SealedEvilInACan: The Forgotten is sealed away in the Gem of Eternity, but the mage from Chapter 0 is foolish enough to lust for it... and breaks it.
* SkillPointReset: You can do this for free at the skill screen.
* SoundOfNoDamage: The game plays a metallic clink if an attack on an enemy is nullified by DamageReduction.
* SplashDamage: Red gems give splash damage in first two games. Lime gems give a multi-hit version (which is likely why red gems were changed). Red takes Lime's multi-hit in Chasing Shadows, while the Barrage spell fires shells that do splash damage as well.

''Chasing Shadows'' contains examples of:
* AbsurdlyHighLevelCap: By stacking Difficulty, Talisman bonus, and Battle Traits, you can easily get billions of XP per level. By the time you reach level 1500-odds, it will still be enough to gain 50 levels a shot.
* AndManGrewProud: How the Forgotten got summoned in the first place.
* BatmanGambit: [[spoiler:The Forgotten's plan to get captured by the wizards enough times for the fake Gems of Eternity to become fully corrupt.]]
* BossInMookClothing: The Giants. Overlaps with DamageSpongeBoss.
* DeathIsCheap: Referenced at the beginning of the game: your body is always hiding in an old tower in the game's easiest level, while the Orb of Presence lets you clear the way of monsters. If they manage to break the orb, the protagonist only needs to make another.
* DualBoss: Demons and Spires occasionally attack in pairs or couples. On higher difficulty, even three or four can be on the battlefield at once.
* DifficultySpike: Once you're past sector P, monsters start having enough armor and HP that you won't make it very far unless you can pull out a grade 5-6 gem on the first wave.
* DiscOneNuke: The Beam attack deals low damage, but hits 10 times per second, making it ridiculously easy to stack specials on a monster. Paired with an Orange gem, it can harvest mana by the thousands as early as in Wave 3. Paired with the black gem, it can make it grow uber powerful in a hurry.
** It becomes a ''self-boosting'' nuke later in the game, in levels where you have access to White gems, which improve the gem's damage and special (i.e. they make it harvest even MORE mana) the more times you hit the Mana cap, giving you a gem that basically upgrades itself for free provided that you spend your Mana wisely.
* EvilEvolves: The Demons start out as merely annoying, but as you clear more sectors, they gain several abilities, such as attacking your orb directly, slowing down your spells' recharge time, spawning and reinforcing monsters, and so on. They even retain all of their abilities if you meet one by replaying a previous level.
* FourIsDeath: Field T1 has four broken orbs with the corpses of their four corresponding wizards nearby. It's also the field where the most spirits appear.
* FunWithAcronyms: The spell you get by obtaining the [[spoiler:fake]] Gem of Eternity is called "Wake of Eternity". [[spoiler:As you find out eventually, it's not just your enemies that it brings woe to.]]
* HealingFactor: All monsters regenerate health now. The Cyan gem and Shrine of Infection can counter it.
* HopeSpot: Towards the end, wizards from the Spiritforge start sending you help with their own gems and towers. [[spoiler:Things go downhill really fast from there.]]
* JumpScare: The Forgotten will regularly and suddenly appear with a ScareChord in later portions of the game. Her appearance also enrages the next few waves, making them stronger, or [[InterfaceScrew disables your HUD]], preventing you from casting spells or moving gems for a while.
* LevelGrinding: While the leveling system only counts the best score for each field for the purpose of leveling up, you need a lot of grinding to get the Shadow Cores needed to upgrade your Talisman and increasing the difficulty and XP yield of levels.
* MookMaker: The Shadows will regularly drop off monsters on the path. Also, Possessed Giants gain the ability to spawn Swarmlings when they're killed.
* MoreDakka: One of the new features of the game gives your gems an extra attack with limited charges that they can use together with their normal attack: the long-ranged, armor piercing [[SniperCannon Bolt]], the continuous-firing [[BeamSpam Beam]], and the multiple explosive [[MacrossMissileMassacre Barrage]] shells.
* MightyGlacier: Spires are nigh-unstoppable beasts who dwarf even your towers and will destroy you with a single hit, and have a cap on the damage they can take from every shot as they make a beeline for your Orb... which takes them about five minutes to reach, which gives an ample window of time to shoot them down.
* NiceJobBreakingItHero: [[spoiler:Whenever a wizard trapped the Forgotten, she corrupted the Gem of Eternity. By going to the Spiritforge and performing the ritual with the fake Gem, you gave her the chance to activate all the corrupted replicas and blow the Spiritforge's gates open. Oops.]]
* OneHitKill: Let a Spire reach your orb, and no amount of Mana and Banishment upgrades will save you.
** Also, if the monster waves run out before you manage to unlock a wizard tower or charge an ensnarement socket, the ritual fails and your orb gets destroyed.
* ShoutOut: The Wake of Eternity icon looks a lot like [[TheRing the iconic image of a certain horror movie]]... which is fitting, since the Forgotten is a [[IncrediblyLamePun dead ringer]] for said movie's antagonist.
* TakingYouWithMe: Demons and Spires will explode when you take them down, demolishing all walls in their vicinity. Not noticing that can let monsters slip through very quickly.
* TripodTerror: Spires, albeit with altogether too many legs for comfort.
* ScratchDamage: All attacks deal at least 1 damage no matter how much armor the monster has.
** Spires cannot be damaged for more than a certain portion of their maximum HP, so continuous fire from several gems is the only way to take them down.

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