| u-sing | 3 | U-Sing | Video game series |
| u6engine | 8 | Ultima VI engine | Software entities |
| ubi.com | 26 | Ubi.com account | Other entities |
| ubiart | 20 | UBIart Framework | Software entities |
| ubisoft-osp | 11 | Ubisoft Online Services Platform | Software entities |
| ubnut | 1 | n.a. | |
| ubunru | 3 | n.a. | |
| ubunt | 3 | n.a. | |
| ubuntu | 7137 | Ubuntu Linux | Software themes |
| ubuntu' | 1 | n.a. | |
| ubuntuzeldaclassicengine | 1 | n.a. | |
| ubutnu | 2 | n.a. | |
| uchronia | 162 | Uchronia | Historical concepts |
| udc | 1 | n.a. | |
| ufo-series | 3 | UFO | Video game series |
| ufoet-series | 2 | UFO: Extraterrestrials | Video game series |
| ufos | 1 | n.a. | |
| uganda | 1 | n.a. | |
| ugc | 142 | User Generated Content | Video game concepts |
| uipointer | 23 | UI pointer | Software concepts |
| uiq | 2 | n.a. | |
| uiq3 | 1 | n.a. | |
| uislider | 1 | n.a. | |
| uk | 1 | n.a. | |
| ukraine | 17 | Ukraine | Locations entities |
| ukrainian | 1 | n.a. | |
| ultima | 180 | Ultima | Video game series |
| ultima7-engine | 38 | Ultima VII | Software entities |
| ultima8-engine | 5 | Ultima VIII engine | Software entities |
| ultimaageofarmageddon | 28 | Ultima: Age of Armageddon | Video game series |
| ultimaageofdarkness | 43 | Ultima: The Age of Darkness | Video game series |
| ultimaageofenlightenment | 39 | Ultima: The Age of Enlightenment | Video game series |
| ultimatehits | 15 | Ultimate hits | Other entities |
| ultimauw | 12 | Ultima Underworld | Video game series |
| ultimawoa | 5 | Ultima Worlds of Adventure | Video game series |
| ultraman | 48 | Ultraman | Culture series |
| ultrasoundace | 1 | n.a. | |
| ultrasoundmax | 1 | n.a. | |
| ultraterrestrials | 5 | Ultraterrestrials | Creatures themes |
| ultraverse | 2 | Ultraverse | Locations concepts |
| ultrix | 1 | n.a. | |
| umbra3 | 7 | Umbra 3 | Software entities |
| uminekononakukoroni | 15 | Umineko no Naku Koro ni | Video game series |
| unalignedenemies | 1 | Unaligned enemies | Other themes |
| unarmedfighting | 967 | Unarmed fighting | Activities themes |
| unattendedevents | 23 | Unattended events | Video game concepts |
| unattendedgameplay | 4 | Unattended gameplay | Video game concepts |
| unboundspeed | 4 | Unbound speed | Software themes |
| unbuntu | 1 | n.a. | |
| uncertainending | 10 | Uncertain ending | Other concepts |
| uncertainreality | 11 | Uncertain reality | Other themes |
| uncertainty | 1 | Uncertainty | Video game concepts |
| uncharted | 2 | The uncharted | Locations themes |
| uncharted-series | 6 | Uncharted | Video game series |
| unchartedwaters-series | 28 | Uncharted Waters | Video game series |
| unchosenone | 2 | The Unchosen One | Other themes |
| unclearcause | 1 | Unclear cause | Video game themes |
| unconfirmed | 3 | Unconfirmed | Other concepts |
| unconnectedextremities | 52 | Unconnected extremities | Cartoon themes |
| unconvincingarmor | 66 | Unconvincing armor | Culture concepts |
| uncooperativeprotagonist | 3 | n.a. | |
| uncoopertiveprotagonist | 2 | n.a. | |
| undead | 1154 | Undead | Creatures themes |
| undeadanimals | 37 | Undead animals | Creatures themes |
| undeadmenace | 59 | Undead menace | Other themes |
| undeadmonsters | 7 | Undead monsters | Creatures themes |
| undeadprotagonist | 78 | Undead protagonist | Creatures themes |
| undefinedattack | 3 | Undefined attack | Video game concepts |
| undefinedelements | 431 | Undefined gameplay elements | Video game concepts |
| undefinedhealing | 4 | Undefined healing | Video game concepts |
| undefinedlocomotion | 4 | Undefined locomotion | Vehicles concepts |
| undefinedsetting | 7 | Undefined setting | Locations themes |
| underash | 2 | Under Ash | Video game series |
| underseashooter | 1 | n.a. | |
| undertaking | 4 | Undertaking | Activities themes |
| underwater | 541 | Underwater | Locations themes |
| underwaterdiving | 297 | Underwater diving | Activities themes |
| underwaterfacility | 20 | Underwater facility | Locations themes |
| underwaterwalking | 41 | Underwater walking | Activities themes |
| underworld | 40 | Land of the dead | Locations entities |
| undirected | 107 | Undirected | Video game concepts |
| undo | 47 | Undo | Video game concepts |
| unduehaste | 8 | Undue haste | Video game themes |
| unethicalscience | 17 | Unethical science | Culture concepts |
| unexpectedsituation | 47 | Unexpected situation | Culture concepts |
| unexplainedelements | 22 | Unexplained elements | Video game concepts |
| unfair | 1 | n.a. | |
| unfinished | 7 | Unfinished | Other themes |
| unfixedbugs | 35 | Unfixed bugs | Other concepts |
| unhealthyundead | 22 | Unhealthy undead | Video game concepts |
| unhinderedfoes | 5 | Unhindered foes | Video game concepts |
| unibiomeworld | 20 | Unibiome world | Locations themes |
| unicorns | 76 | Unicorns | Creatures themes |
| unicycle | 12 | Unicycle | Vehicles entities |
| unification | 54 | Unification | Other themes |
| unigine | 18 | Unigine | Software entities |
| uniloc | 1 | Uniloc copy protection | Software entities |
| unintentional | 2 | n.a. | |
| uniqueminions | 58 | Unique minions | Other concepts |
| uniqueprotagonist | 66 | Unique protagonist | Creatures themes |
| unitequipment | 13 | Unit equipment | Video game concepts |
| unitlimit | 70 | Unit limit | Video game concepts |
| unitstacks | 20 | Unit stacks | Video game concepts |
| unitstances | 10 | Unit stances | Video game concepts |
| unity | 2 | n.a. | |
| unity-engine | 1515 | Unity | Software entities |
| unity-rpgkit | 1 | Unity RPG Kit | Software themes |
| unity2d | 2 | n.a. | |
| unity5-engine | 5 | Unity 5.x | Software entities |
| unitybyforce | 10 | Unity by force | Other themes |
| univac | 4 | n.a. | |
| universal79-hw | 6 | Universal 79 Arcade hardware | Hardware entities |
| universal83-hw | 6 | Universal '83 Arcade hardware | Hardware entities |
| universalammo | 14 | Universal ammo | Tools concepts |
| universalbinary | 3 | Universal binary | Software concepts |
| universallanguage | 41 | Universal language | Culture themes |
| universaltheatre | 20 | Universal theatre | Other concepts |
| universeatwar | 2 | Universe at War | Video game series |
| unix | 39 | UNIX operating system | Software themes |
| unknownengine | 1 | Unknown engine | Software themes |
| unknowngenre | 2 | Unknown genre | Game genre themes |
| unknownpast | 124 | Unknown past | Other concepts |
| unknownproportions | 1 | Unknown proportions | Video game themes |
| unlicenced | 1 | n.a. | |
| unlicensed | 48 | Unlicensed content | Video game concepts |
| unlikelysentients | 7 | Unlikely sentients | Creatures themes |
| unlimitedammo | 289 | Unlimited ammo | Tools concepts |
| unlimitedlives | 82 | Unlimited lives | Video game concepts |
| unlimitedsaves | 2 | Unlimited Saves | Video game concepts |
| unloading | 24 | Unloading | Activities themes |
| unlockable-abilities | 2 | Unlockable content: Abilities | Video game concepts |
| unlockable-art | 19 | Unlockable content: Art | Video game concepts |
| unlockable-campaigns | 3 | Unlockable content: Campaigns | Video game concepts |
| unlockable-characters | 75 | Unlockable content: Characters | Video game concepts |
| unlockable-classes | 4 | n.a. | |
| unlockable-costumes | 43 | Unlockable content: Costumes | Video game concepts |
| unlockable-difficulty | 38 | Unlockable content: Difficulty options | Video game concepts |
| unlockable-items | 64 | Unlockable content: Items / Equipment | Video game concepts |
| unlockable-modes | 34 | Unlockable content: Game modes | Video game concepts |
| unlockable-options | 6 | Unlockable content: Options | Video game concepts |
| unlockable-vehicles | 7 | Unlockable content: Vehicles | Video game concepts |
| unlockablecontent | 13 | Unlockable content | Video game concepts |
| unlockableroutes | 1 | n.a. | |
| unnecessarykilling | 63 | Killing is unnecessary | Video game concepts |
| unnkulia | 12 | Unnkulia Series | Video game series |
| unnoticedbynormals | 14 | Unnoticed by normals | Other themes |
| uno | 19 | Uno | Traditional themes |
| unofficial | 19 | Unofficial | Video game concepts |
| unorthodoxweapons | 22 | Unorthodox weapons | Tools themes |
| unprofessionalbehaviour | 1 | n.a. | |
| unready | 1 | Unready | Culture concepts |
| unreal | 8 | Unreal | Video game series |
| unrealdevkit | 37 | Unreal Development Kit | Software entities |
| unrealeased | 1 | n.a. | |
| unrealengine | 111 | Unreal Engine | Software series |
| unrealengine1 | 49 | Unreal Engine 1 | Software entities |
| unrealengine2 | 103 | Unreal Engine 2 | Software entities |
| unrealengine3 | 333 | Unreal Engine 3 | Software entities |
| unrealengine4 | 149 | Unreal Engine 4 | Software entities |
| unrealengine5 | 12 | Unreal Engine 5 | Software entities |
| unrealistictools | 2 | Unrealistic tools | Tools themes |
| unrealtournament | 20 | Unreal Tournament | Video game series |
| unrelatedobjectives | 2 | Unrelated objectives | Video game concepts |
| unrelatedsequel | 12 | Unrelated sequel | Video game concepts |
| unreleased | 3 | n.a. | |
| unreliablenarrator | 53 | Unreliable narrator | Culture concepts |
| unrestrictedviolence | 105 | Unrestricted violence | Other themes |
| unrootedplants | 26 | Mobile Plants | Creatures themes |
| unseencharacters | 2 | Unseen characters | Creatures themes |
| unseeninformers | 1 | Unseen informers | Video game concepts |
| unseenprotagonist | 186 | Unseen protagonist | Creatures themes |
| unskippablenoninteraction | 6 | Unskippable non-interaction | Video game concepts |
| unsteadycamera | 10 | Unsteady camera | Other concepts |
| unsteam | 1 | Redeemed from Steam | Other themes |
| unsymmetricmotion | 1 | Unsymmetric Motion | Video game concepts |
| untiy3d | 1 | n.a. | |
| untoldlegends | 3 | Untold Legends | Video game series |
| unusedcontent | 4 | Unused content | Other concepts |
| unusualangles | 1 | n.a. | |
| unusualmounts | 83 | Unusual mounts | Creatures themes |
| unusualprotagonist | 178 | Unusual protagonist | Creatures themes |
| unusualtools | 5 | Unusual tools | Tools concepts |
| unuty3d | 2 | n.a. | |
| unvoicedprotagonist | 31 | Unvoiced protagonist | Video game concepts |
| unwantedresponsibility | 5 | Unwanted responsibility | Culture concepts |
| unwieldyweapons | 33 | Unwieldy weapons | Tools themes |
| updateretcon | 4 | Update retcon | Other concepts |
| upgrades | 9 | n.a. | |
| upgrades-abilities | 26 | Upgrades: Abilities / Skills | Video game concepts |
| upgrades-capacity | 6 | Upgrades: Carry capacity | Video game concepts |
| upgrades-health | 18 | Upgrades: Health | Video game concepts |
| upgrades-other | 9 | Upgrades: Other | Video game concepts |
| upgrades-permanent | 78 | Permanent upgrades | Video game concepts |
| upgrades-transient | 59 | Transient upgrades | Video game concepts |
| upgradesystem | 486 | Upgrade system | Video game concepts |
| upkeep | 49 | Upkeep | Other concepts |
| uplay | 40 | Uplay | Software entities |
| upliftedanimals | 12 | Uplifted animals | Creatures themes |
| uplsf-hw | 5 | UPL "sprite framebuffer" Arcade System | Hardware entities |
| upnp | 16 | Universal Plug and Play | Hardware themes |
| upsidedown | 7 | Upside down | Video game concepts |
| uranus | 16 | Uranus | Locations themes |
| urbanfantasy | 172 | Urban fantasy | Fiction genre themes |
| urbanlegend | 3 | Urban Legend | Culture themes |
| urbanlegends | 6 | Urban legends | Culture concepts |
| urealengine | 1 | n.a. | |
| urho3d | 1 | n.a. | |
| urophilia | 1 | Urophilia | Other themes |
| ursineprotagonist | 78 | Ursine protagonist | Creatures themes |
| ursines | 133 | Ursines | Creatures entities |
| ursinoids | 12 | Ursinoids | Creatures themes |
| urukhai | 5 | Uruk-hai | Creatures themes |
| uruseiyatsura | 14 | Urusei Yatsura | Culture series |
| usa | 718 | United States of America | Locations entities |
| usacom | 1 | n.a. | |
| usagereporting | 14 | Usage reporting | Software concepts |
| usc-paid | 42 | Ubuntu Software Center - Paid for Application | Software themes |
| use | 2 | n.a. | |
| uselessadults | 10 | Useless adults | Culture themes |
| uselessallies | 13 | Useless allies | Video game concepts |
| utah | 5 | Utah, USA | Locations themes |
| utahraptor | 2 | Utah Raptor | Creatures themes |
| utawarerumono | 21 | Utawarerumono | Video game series |
| utilityaircraft | 3 | Utility aircraft | Vehicles themes |
| uvl- | 2 | n.a. | |
| uvl-confusable | 2844 | UVL maintenance: Confusable | Other concepts |
| uvl-confusableamphibianprotagoni | 1 | n.a. | |
| uvl-corruptedtext | 1 | UVL: Corrupted text | Other themes |
| uvl-deleterequest | 33 | UVL: Delete Request | Other themes |
| uvl-descriptionincomplete | 201 | UVL: Incomplete description | Other themes |
| uvl-display-missing | 2 | UVL Maintenance: Possibly Missing Display Information | Hardware themes |
| uvl-distributors | 1 | UVL: Distributors | Other entities |
| uvl-englishneeded | 1 | UVL: English Translation Needed | Other themes |
| uvl-fantitle | 71 | UVL: Fan invented title listed | Other themes |
| uvl-fantranslation | 190 | UVL: Fan translated title listed | Other themes |
| uvl-gallerycleanup | 5 | UVL: Gallery cleanup task | Other themes |
| uvl-imageediting | 38 | UVL: Image editing needed | Other themes |
| uvl-imageissues | 1 | UVL: Image Issues | Other concepts |
| uvl-imagenotfrontpage | 1 | UVL: Images are safe, but not 'front page appropriate' | Other concepts |
| uvl-imagequality | 221 | UVL: A higher quality image should be sought | Other themes |
| uvl-insignificanttags | 1 | UVL: Insignificant tags | Other themes |
| uvl-license-pending | 2 | UVL: License Pending | Software concepts |
| uvl-missingimages | 692 | UVL: Missing images | Other themes |
| uvl-missingmedia | 332 | UVL: Missing media | Other themes |
| uvl-missingmediauvl-missingmedia | 4 | n.a. | |
| uvl-missingrelations | 26 | UVL: Missing game relations | Other themes |
| uvl-misspelledtitle | 42 | UVL: Includes commonly used misspelled title | Other themes |
| uvl-multiplayerinfo | 1 | UVL Maintenance: Multiplayer Info is incomplete | Other themes |
| uvl-originaltitlemissing | 228 | UVL: Original title missing | Other themes |
| uvl-osversion | 112 | Maintenance Tag: Unknown Requirements for OS | Other concepts |
| uvl-partialtitle | 14 | UVL: Partial title listed | Video game concepts |
| uvl-phonetictitle | 1 | UVL Maintenance: Phonetic Title Listed | Other concepts |
| uvl-platform-limitation | 358 | UVL: Platform/Operating System Limitation | Other themes |
| uvl-realtitle | 58 | UVL: Real Title | Video game concepts |
| uvl-releases | 76 | OBSOLETE - UVL: Multiple releases | Video game concepts |
| uvl-romanizationmissing | 14 | UVL: Romanization missing | Other themes |
| uvl-searchelp | 301 | UVL: Search help title | Other themes |
| uvl-sku | 57 | UVL maintenance: SKU problem | Other concepts |
| uvl-spielengames | 2 | UVL Maintenance: Linux Spiele & Games | Other themes |
| uvl-steamcoveragecheck | 51 | UVL Steam Coverage Check | Other concepts |
| uvl-sync | 7 | UVL: Version synchronization | Other concepts |
| uvl-techlimitation | 160 | A Technical Limitation in UVL | Other themes |
| uvl-temporarytags | 1 | UVL: Temporary Tags | Other themes |
| uvl-tiein | 2245 | UVL Maintenance: Generic tie-in tag | Other concepts |
| uvl-unsearchable | 1 | n.a. | |
| uvl-verifyexistance | 2 | n.a. | |
| uvl-verifyexixtence | 1 | n.a. | |
| uvl-workingtitle | 210 | UVL: Working title listed | Video game concepts |
