Steamworld Quest: Hand of Gilgamech (Switch): https://www.nintendo.com/games/detail/steamworld-quest-hand-of-gilgamech-switch/
Octahedron: Transfixed Edition (PC): https://store.steampowered.com/app/434660/Octahedron_Transfixed_Edition/

@IVT - Those have been added!

Crazy Frog Racer (The one that currently exists on Completionator, Crazy Frog: Arcade Racer, is Crazy Frog Racer 2 in PAL region. CFR 1 does not exist on site.)
Driven to Destruction - PAL naming for Test Drive: Eve of Destruction
MotoGP - The one on Completionator is the THQ version. A Namco version exists. (https://gamefaqs.gamespot.com/ps2/370604-motogp)
SCAR Squadra Corse Alfa Romeo

Totally accurate battle simulator (game): https://store.steampowered.com/app/508440/Totally_Accurate_Battle_Simulator/
Swords and Sandals Classic Collection (bundle of semi-old games): https://store.steampowered.com/app/1055430/Swords_and_Sandals_Classic_Collection/

Cytus Alpha - https://www.nintendo.com/games/detail/cytus-a-switch/

The Division: Underground: hiddenSurvival/
The Division: Last Stand:

@RavenKujikawa - Crazy Frog Racer has been added. Crazy Frog: Arcade Racer, Alfa Romeo Racing Italiano (US name for the SCAR title), and MotoGP have all been updated and alias' added. Upon selecting an EU region release, you will see the EU name listed in your collection.

@kw4s - That one has been added!

@Jaguar1367 - Those have been added!

@XxThundaxX - TABS was added. Swords and Sandals Classic Collection will have to be done by @moho_00.

Initial D: Street Stage - https://www.giantbomb.com/initial-d-street-stage/3030-21830/

@Hentai Wizard - That has been added!

Swords And Soldiers HD - https://store.steampowered.com/app/63500/Swords_and_Soldiers_HD/

2 more bundles to add alongside the one from before (first in this post)
Swords and Sandals Classic Collection (bundle of semi-old games): https://store.steampowered.com/app/1055430/Swords_and_Sandals_Classic_Collection/
DEAD RISING TRIPLE PACK (Includes DR1, DR2 and DR: Off the record): https://store.steampowered.com/bundle/1399/Dead_Rising_Triple_Pack/
NEKOPARA COMPLETE EDITION (includes V0, V1, V2, V3): https://store.steampowered.com/bundle/676/NEKOPARA_complete_edition/

@XxThundaxX - Dead Rising Triple Pack has been added, but I wasn't sure about Nekopara. I'm not familiar with the series, but I do know the episodes have trickled out and I'm wondering if V4 will be added to the Complete Edition once it's released, since Steam likes to change things up sometimes. Also, I'm a little unclear on what to add for Swords and Sandals, at least for the 2nd and 3rd games. We have both of them loaded under different titles, so not sure if what's in the bundle (they both have different titles there) is the same or if we need separate entries.

Far Cry Instincts: Predator is a compilation of Far Cry Instincts and Far Cry Evolution. If that can be converted please.

Is Far Cry Instincts: Predator a true compilation, meaning you can select either of the games or is it more of a new game that combines them together as one continuous experience? I'm not familiar with it at all, but I know in cases like Evolution Worlds for GameCube, multiple games are merged into one, even though it's more or less two games that were originally released individually.

@moho_00 If you'd prefer just not to add them as bundles that's okay, it's a pretty messy series not only imo but in the dev's opinion too. But just in case I gathered some more info:
Here's a post by the developer himself about the series, ignoring most of it, ctrl+f search "exhaustive" and see that comment by the developer. All the games he listed are his own 'official' games, whilst many other 'reduxes' (or remakes) of his games were made by others, alongside new games in the series that weren't made by him. https://www.reddit.com/r/IndieGaming/comments/a2c23z/im_the_guy_who_made_those_old_flash_games_swords/

Simply put, the steam collection includes 5 of his original games, some of which are already loaded, whilst some of the games already added to completionator are reduxes and originals made by other companies.
"Swords and Sandals Classic Collection" on steam includes the following 5 games ( https://store.steampowered.com/app/1055430/Swords_and_Sandals_Classic_Collection/ ):
-"Swords and Sandals I : Gladiator" ( https://completionator.com/Game/Details/46610 )
-"Swords and Sandals II : Emperor's Reign" (The original version of "Swords and Sandals 2 Redux: Maximus Edition" is already in completionator, and is an 'unofficial' remaster of Emporer's Reign)
-"Swords and Sandals III : Gladiae Ultratus" (I believe it is a different game from "Swords and Sandals III: Solo Ultratus", which I am guessing was an 'unofficial' remake of it as the developer did not list it in the reddit thread. "Swords and Sandals III: Multiplae Ultratus" is the multiplayer version (separate game) from Gladiae Ultratus)
-"Swords and Sandals IV : Tavern Quests" ( https://completionator.com/Game/Details/46609 )
-"Swords and Sandals Crusader" ( https://completionator.com/Game/Details/46608 )
The two games marked "*" at the start are not yet in completionator.

Also out of interest is the issue with modifying an already existing bundle/compilation that some people would have just the old version of the bundle or something else? (Like you said about Nekopara's bundle)

Also some other games/bundles I would like added:
Everybody's Golf VR (PSVR): https://www.playstation.com/en-au/games/everybodys-golf-vr-ps4/
Killing Floor Double Feature (PS4/PSVR): https://www.playstation.com/en-us/games/killing-floor-double-feature-ps4/ (Includes: Killing Floor 2, Killing Floor Incursion)
KINGDOM HEARTS All-In-One Package (PS4)
https://store.playstation.com/en-au/product/EP0082-CUSA12025_00-KINGDOMHEARTSALL?emcid=em-st-196812&et_cid=em_362468&et_rid=113155090
(Includes: KINGDOM HEARTS HD 1.5 + 2.5 ReMIX, KINGDOM HEARTS HD 2.8 Final Chapter Prologue, KINGDOM HEARTS III)

Most of these games are future upcoming releases. A lot of these are either going to be exclusive or temporarily exclusive to the Epic Games storefront. I'm kinda holding out for at least some of these to come out on Steam or maybe even on the Switch possibly (either outcome seems unlikely at this point, but you never know!). But until then, I was hoping to be able to track them on my wishlist in the meantime.

Ghost of Tsushima (PS4)
https://www.playstation.com/en-us/games/ghost-of-tsushima-ps4/

Concrete Genie (PS4)
https://www.playstation.com/en-us/games/concrete-genie-ps4/

Malicious Fallen (PS4, Digital Only)
https://www.playstation.com/en-us/games/malicious-fallen-ps4/

Vane (PS4, DIgital Only)
https://www.playstation.com/en-us/games/vane-ps4/

Utawarerumono: Prelude to the Fallen (PS4 & PS VITA)
https://nisamerica.com/games/utawarerumono-prelude-to-the-fallen/

Atelier Lulua: The Scion of Arland (Switch, PS4, & Steam)
http://www.ateliergames.eu/lulua/

Close to the Sun
https://www.epicgames.com/store/en-US/product/close-to-the-sun/home

Observation
https://www.epicgames.com/store/en-US/product/observation/home

Hades
https://www.epicgames.com/store/en-US/product/hades/home

Spellbreak
https://www.epicgames.com/store/en-US/product/spellbreak/home

Journey to the Savage Planet
https://www.epicgames.com/store/en-US/product/journey-to-the-savage-planet/home

Rebel Galaxy Outlaw
https://www.epicgames.com/store/en-US/product/rebel-galaxy-outlaw/home

Dauntless
https://www.epicgames.com/store/en-US/product/dauntless/home

Day Of The Tentacle/Sam And Max Hit The Road pack - PC

Came across a couple games for the Nintendo DS that haven't been added yet:

"Asterix Brain Trainer" from Atari;
"Best of Tests" from Neko Entertainment;
"Big Catch: Bass Finishing" from 505 Games;
"Brain Buster" from 505 Games;
"Bratz Ponyz" from The Game Factory;
"Clever! Das Spiel, das Wissen schafft" from SevenOne Intermedia GmbH;
"Clever Kids: Dino Land" from Midas Interactive;
"Clever Kids: Pony World" from Midas Interactive;
"Das weiß doch jedes Kind!" from Mindscape;
"Die drei Fragezeichen - Das Geheimnis der Geisterinsel" from DTP Entertainment AG;
"English Training - Spielend Englisch lernen" from Plato;
"Essential Sudoku DS" from D3;
"Flipper Critters DS" from Conspiracy Entertainment;
"Garfield's Nightmare" from The Game Factory;
"Labyrinth" aka "Mawashite Koron" from Taito; the remake of Cameltry for DS
"Left or Right: Ambidextrous Challange" from 505 Games;
"Looney Tunes: Cartoon Conductor" from Eidos;
"Professor Kageyama's Maths Training" from Nintendo;
"The Professor's Brain Trainer - Logic" from 505 Games;
"Scotland Yard" from DTP Entertainment AG;

Sanrio Timenet: Kako Hen
Sanrio Timenet: Mirai Hen
2 editions of the same game - http://sanrio.shoutwiki.com/wiki/Sanrio_Timenet:_Kako_Hen_and_Mirai_Hen

Love Bites - https://store.steampowered.com/app/617970/Love_Bites/?curator_clanid=2717761
Cursed Lands - https://store.steampowered.com/app/584940/Ambers_Magic_Shop/?curator_clanid=2717761
Amber's Magic Shop - https://store.steampowered.com/app/584940/Ambers_Magic_Shop/?curator_clanid=2717761
Ana The Game - https://store.steampowered.com/app/811090/Ana_The_Game/
Astoria: The Holders of Power Saga - https://store.steampowered.com/app/669380/Astoria_The_Holders_of_Power_Saga/
Asura Valley - https://store.steampowered.com/app/779320/Asura_Valley/
Bad Neighbor - https://store.steampowered.com/app/939270/Bad_Neighbor/
Black Home 2 - https://store.steampowered.com/app/849070/Black_Home_2/
Blood 'n Bikinis - https://store.steampowered.com/app/596200/Blood_n_Bikinis/
BuriedTown - https://store.steampowered.com/app/432640/BuriedTown/
CHANGE: A Homeless Survival Experience - https://store.steampowered.com/app/926140/CHANGE_A_Homeless_Survival_Experience/
Chaos Drift - https://store.steampowered.com/app/596530/Chaos_Drift
Elderine: Dreams to Destiny - https://store.steampowered.com/app/535350/Elderine_Dreams_to_Destiny/
Eternal Realm - https://store.steampowered.com/app/372670/Eternal_Realm/
GALER: Plague of Heroes - https://store.steampowered.com/app/508330/GALER_Plague_of_Heroes/
Good Company - https://store.steampowered.com/app/911430/Good_Company/
Hawks Tactical - https://store.steampowered.com/app/571550/Hawks_Tactical/
HYBRIS - Pulse of Ruin - https://store.steampowered.com/app/965670/Niplheims_Hunter__Branded_Azel/
Nobunaga's Shadow - https://store.steampowered.com/app/868930/Nobunagas_Shadow/
Ooblets - https://store.steampowered.com/app/593150/Ooblets/
Paws and Soul - https://store.steampowered.com/app/911510/Paws_and_Soul/
Romancing Monarchy - https://store.steampowered.com/app/890940/Romancing_Monarchy/
Room 42 - https://store.steampowered.com/app/711480/Room_42/
Sacrament - https://store.steampowered.com/app/734380/Sacrament/
Seers Isle - https://store.steampowered.com/app/738650/Seers_Isle/
Skautfold: Into the Fray - https://store.steampowered.com/app/893610/Skautfold_Into_the_Fray/
Tales of Nebezem RPG: Red Peril - https://store.steampowered.com/app/1034560/Tales_of_Nebezem_RPG_Red_Peril/
The Executioner - https://store.steampowered.com/app/739130/The_Executioner/
The Mercury Man - https://store.steampowered.com/app/740200/The_Mercury_Man/
The Orphaned Soul - https://store.steampowered.com/app/911690/The_Orphaned_Soul/
The Singularity Wish - https://store.steampowered.com/app/819780/The_Singularity_Wish/
The Tavern - https://store.steampowered.com/app/681970/The_Tavern/
The Unclogging: An Unsanitary Saga - https://store.steampowered.com/app/661410/The_Unclogging_An_Unsanitary_Saga/
Underdone - https://store.steampowered.com/app/666040/Underdone/
Viviette - https://store.steampowered.com/app/883070/Viviette/
Wild Romance: Mofu Mofu Edition - https://store.steampowered.com/app/748480/Wild_Romance_Mofu_Mofu_Edition/
X-COM: Apocalypse - https://store.steampowered.com/app/7660/XCOM_Apocalypse/
Yukie: A Japanese Winter Fairy Tale - https://store.steampowered.com/app/352810/Yukie_A_Japanese_Winter_Fairy_Tale/

Once Upon A Crime In The West
https://www.giantbomb.com/once-upon-a-crime-in-the-west/3030-73267/

As for Far Cry Instincts Predator...
Far Cry Wiki :
Far Cry Instincts: Predator, a Xbox 360 title, was released March 27, 2006. Predator is a graphically enhanced version of both Far Cry Instincts and Far Cry Instincts: Evolution.

Wikipedia :
Far Cry Instincts: Predator, an Xbox 360 title, was released on the same day as Evolution. It includes graphically enhanced versions of both Far Cry Instincts and Evolution. It featured a map editor in which the player can create maps. Characters on online play are basic clones of Jack Carver but can be edited, the character still has the tattoo "Karma" on his shooting arm.

Seems like the games are still separate. Probably choose them from a menu.

Darius Cozmic Collection - https://www.play-asia.com/darius-cozmic-collection/13/70c5fx
includes:
* Darius
* Darius II
* Sagaia - https://completionator.com/Game/Details/29577
* Darius Gaiden - https://completionator.com/Game/Details/353

edit:
* Do You Like Horny Bunnies? 1 & 2 Bundle Pack - https://www.jlist.com/hset006 (NSFW obviously) - a physical release bundle that includes https://www.completionator.com/Game/Details/22735 and https://www.completionator.com/Game/Details/22736

edit2:
and while we're at it, JAST USA Memorial Collection ( https://completionator.com/Game/Details/22838 ) could be renamed to JAST USA Memorial Collection Special Edition - there are 2 collections, one ( original - https://vndb.org/r1673 ) was released in 2002 and contains just 3 games on a single CD and the second ( 2012 reissue - https://vndb.org/r21557 ) adds 2 additional games, a gallery and is on a DVD. Also uses different cover (the one in completionator database, original cover looks like this: https://www.play-asia.com/jast-usa-memorial-collection/13/701xz2 )

PC:
Estranged: Act 1 - https://www.giantbomb.com/estranged-act-1/3030-58856/

Nintendo Switch :
Super One More Jump - https://www.giantbomb.com/super-one-more-jump/3030-65636/
The Office Quest - https://www.giantbomb.com/the-office-quest/3030-70502/

ChromaGun VR (PSVR) https://store.playstation.com/en-au/product/EP1141-CUSA11216_00-CHROMAGUNPSVR000
Space Junkies (PSVR) https://store.playstation.com/en-au/product/EP0001-CUSA14019_00-SPACEJUNKIESGAME
Blood & Truth (PSVR) https://store.playstation.com/en-au/product/EP9000-CUSA11098_00-BLDTRTHPREORDPSN