The following is a list of virtually every game given away via Epic since they started their regular AAA and decent indie arcade game giveaways back in December 2018.
I missed a couple of them and there are omissions where a game has been given away for the second time; for example the recent daily Christmas giveaways included two games previously given away, i.e. Mutant Year Zero: Road to Eden and Control.
They have given away other games prior to 2018 and their remake of Unreal Tournament which has been in a pre-alpha state for well over a decade and has been free to download and play HERE since it was released as a pre alpha. I've seen the game from it's early beginnings to the latest version and IMO is well worth checking out; especially if you enjoyed previous iterations of Unreal Tournament; for example, my favourites include Unreal Tournament 2004 and Unreal Tournament 3 (2007).
Sadly development of Unreal Tournament ceased a few years ago when Fortnite became really popular. The CEO of Epic games has said development is dead; however it will remain in store and playable for anyone who wishes to play the game. What is available is worth playing with friends. The last time I played it last year, it was still inhabited by other players. Earlier versions of the game still have active modding communities, so it may be worth checking out those games when they are on sale. Apparently Epic have been talking to GOG with a view to re-releasing previous versions on GOG and their own store. Personally I have terabytes of mods for all of the Unreal Tournament games from 2003, 2004 and 2007.
Also permanently available for free via Epic are Antstream Arcade, Rogue Company, Idle Champions of the Forgotten Realms, Paladins, SMITE, Trackmania.
Idle Champions, the popular clicker game is listed in the following list of games given away, but it also included around £100 worth of additional content in the form of booster packs that added various new characters, speed ups, and other perks.
The following is a list of most games given away (minus a couple I missed, plus any repeats. The list starts with the most recent game:
The next giveaway is Thursday 6th January 2022
12/30/2021 Tomb Raider trilogy (unconfirmed)
12/30/2021 Salt and Sanctuary
12/29/2021 Moving Out
12/28/2021 Mages of Mystralia
12/25/2021 Prey
12/24/2021 Pathfinder: Kingmaker - Enhanced Plus Edition
12/24/2021 Vampyr
12/21/2021 Second Extinction™
12/20/2021 Loop Hero
12/19/2021 The Vanishing of Ethan Carter
12/17/2021 Neon Abyss
12/17/2021 Shenmue III - Standard Edition
12/15/2021 Prison Architect
12/14/2021 Godfall Challenger Edition
12/3/2021 while True: learn()
12/3/2021 Dead by Daylight
11/26/2021 Antstream Arcade
11/26/2021 Antstream - Epic Welcome Pack
11/26/2021 theHunter: Call of the Wild™
11/18/2021 Never Alone (Kisima Ingitchuna)
11/18/2021 KID A MNESIA EXHIBITION
11/18/2021 Guild of Dungeoneering
11/17/2021 Rogue Company Season Four Epic Pack
11/13/2021 Tiny Tina's Assault on Dragon Keep: A Wonderla...
11/5/2021 Aven Colony
10/29/2021 DARQ: Complete Edition
10/21/2021 Among the Sleep - Enhanced Edition
10/14/2021 Paladins Epic Pack
10/14/2021 Stubbs the Zombie in Rebel Without a Pulse
10/11/2021 Europa Universalis IV: Evangelical Majors Unit...
10/11/2021 Europa Universalis IV: Catholic Majors Unit Pa...
10/11/2021 Europa Universalis IV: Songs of Yuletide
10/8/2021 Paladins
10/7/2021 PC Building Simulator
10/1/2021 Europa Universalis IV
9/17/2021 Tharsis
9/17/2021 Speed Brawl9/10/2021 Sheltered
9/10/2021 Nioh: The Complete Edition
9/3/2021 Yoku's Island Express
8/28/2021 Automachef
8/26/2021 Saints Row®: The Third™ Remastered
8/21/2021 Void Bastards
8/21/2021 Yooka-Laylee
8/7/2021 A Plague Tale: Innocence
8/7/2021 Far Cry 5 Free Trial Weekend
8/1/2021 Train Sim World 2
8/1/2021 Mothergunship
7/24/2021 Defense Grid: The Awakening
7/23/2021 Verdun
7/9/2021 Ironcast
7/9/2021 Bridge Constructor The Walking Dead
7/3/2021 The Spectrum Retreat
6/25/2021 Sonic Mania
6/25/2021 Horizon Chase Turbo
6/18/2021 Overcooked! 2
6/18/2021 Hell is other demons
6/10/2021 Control
6/9/2021 Genshin Impact
6/4/2021 Frostpunk
5/28/2021 Among Us
5/26/2021 Diabotical
5/26/2021 Trackmania
5/26/2021 Dauntless
5/20/2021 NBA 2K21
5/17/2021 Scavengers
5/14/2021 The Lion's Song
5/7/2021 Exclusive Starter Pack
5/7/2021 Pine
4/29/2021 Idle Champions of the Forgotten Realms
4/29/2021 Rogue Company
4/23/2021 Hand of Fate 2
4/20/2021 Deponia: The Complete Journey
4/20/2021 The First Tree
4/20/2021 Ken Follett's The Pillars of the Earth
4/9/2021 3 out of 10: Season Two
3/29/2021 Creature in the Well
3/18/2021 The Fall
3/7/2021 Wargame: Red Dragon
2/28/2021 Sunless Sea
2/18/2021 Rage 2
2/18/2021 Absolute Drift
2/12/2021 Halcyon 6
2/6/2021 Metro: Last Light Redux
1/29/2021 Dandara: Trials of Fear Edition
1/22/2021 Galactic Civilizations III
1/14/2021 STAR WARS™ Battlefront™ II: Celebration Editio...
1/8/2021 Crying Suns Demo
1/8/2021 Crying Suns
12/31/2020 Jurassic World Evolution
12/29/2020 Solitairica
12/28/2020 Stranded Deep
12/27/2020 Night in the Woods
12/27/2020 My Time at Portia
12/21/2020 Alien: Isolation
12/18/2020 Cities: Skylines
12/10/2020 Tyranny - Gold Edition
12/10/2020 Pillars of Eternity - Definitive Edition
12/10/2020 Cave Story+
11/28/2020 MudRunner - Old Timers DLC
11/28/2020 MudRunner - Valley DLC
11/28/2020 MudRunner - Ridge DLC
11/28/2020 MudRunner
11/7/2020 Dungeons 3
10/31/2020 Ghostbusters: The Video Game Remastered
10/31/2020 Blair Witch
10/22/2020 Layers of Fear 2
10/22/2020 Costume Quest 2
10/18/2020 Amnesia: A Machine for Pigs
10/8/2020 Rising Storm 2: Vietnam
10/8/2020 Pikuniku
9/24/2020 RollerCoaster Tycoon® 3: Complete Edition
9/18/2020 Stick It To The Man!
9/18/2020 Watch Dogs 2
9/18/2020 Football Manager 2020
9/11/2020 Where The Water Tastes Like Wine
9/11/2020 Railway Empire
9/5/2020 3 out of 10, EP 5: "The Rig Is Up!"
9/5/2020 Into The Breach
8/30/2020 3 out of 10, EP 4: "Thank You For Being An Ass
8/27/2020 Shadowrun Collection
8/27/2020 HITMAN
8/24/2020 Delores: A Thimbleweed Park mini-adventure
8/22/2020 3 out of 10 Episode 3: Pivot Like A Champion
8/21/2020 God's Trigger
8/19/2020 3 Out of 10 Episode 2 Foundation 101
8/13/2020 The Alto Collection
8/13/2020 Remnant: From the Ashes
8/13/2020 A Total War Saga: TROY
8/9/2020 Wilmot's Warehouse
8/9/2020 3 Out of 10 Ep 1 Welcome to Shovelworks
7/31/2020 Superbrothers: Sword & Sworcery EP
7/31/2020 Barony
7/31/2020 20XX
7/23/2020 Tacoma
7/23/2020 Next Up Hero
7/18/2020 Torchlight II
7/9/2020 The Escapists 2
7/9/2020 Lifeless Planet: Premier Edition
7/9/2020 Killing Floor 2
7/3/2020 Hue
6/26/2020 Stranger Things 3: The Game
6/26/2020 AER Memories of Old
6/18/2020 Pathway
6/11/2020 ARK Crystal Isles
6/11/2020 ARK Valguero
6/11/2020 ARK The Center
6/11/2020 ARK Ragnarok
6/11/2020 ARK Editor
6/11/2020 ARK: Survival Evolved
5/29/2020 Sludge Life
5/28/2020 Borderlands: The Handsome Collection
5/23/2020 Sid Meier's Civilization VI
5/17/2020 Grand Theft Auto V
5/10/2020 Death Coming
5/1/2020 Crashlands
5/1/2020 Amnesia: The Dark Descent
4/23/2020 For The King
4/16/2020 Wheels of Aurelia
4/16/2020 Just Cause 4
4/11/2020 Magic The Gathering Arena
4/11/2020 Sherlock Holmes Crimes and Punishments
4/11/2020 Close to the Sun
4/3/2020 Hob
4/3/2020 Gone Home
4/3/2020 Totally Reliable Delivery Service
3/28/2020 Figment
3/28/2020 Tormentor X Punisher
3/28/2020 World War Z
3/28/2020 Drawful 2
3/28/2020 Epic Free Bundle
3/20/2020 Watch Dogs Standard Edition
3/20/2020 The Stanley Parable
3/13/2020 Mutazione
3/13/2020 A Short Hike
3/13/2020 Anodyne 2: Return To Dust
3/11/2020 GoNNER
3/11/2020 Offworld Trading Company
2/29/2020 InnerSpace
2/22/2020 Assassins Creed Syndicate Standard Edition
2/22/2020 Faeria
2/13/2020 Aztez
2/13/2020 Kingdom Come: Deliverance
2/8/2020 Ticket to Ride
2/8/2020 Carcassonne
1/31/2020 Farming Simulator 19
1/24/2020 The Bridge
1/17/2020 Horace
1/9/2020 Sundered Eldritch Edition
1/1/2020 Steep
1/1/2020 Darksiders II Deathinitive Edition
1/1/2020 Darksiders Warmastered Edition
12/29/2019 The Talos Principle
12/28/2019 Shadow Tactics: Blades of the Shogun
12/27/2019 Faster Than Light
12/26/2019 Totally Accurate Battle Simulator
12/23/2019 Ape Out
12/23/2019 Little Inferno
12/21/2019 SUPERHOT
12/20/2019 Towerfall Ascension
12/14/2019 The Escapists
12/14/2019 The Wolf Among Us
12/5/2019 Jotun Valhalla Edition
12/4/2019 Rayman Legends
11/22/2019 Bad North Jotunn Edition
11/15/2019 The Messenger
11/14/2019 Nuclear Throne
11/14/2019 RUINER
10/31/2019 SOMA
10/31/2019 Costume Quest
10/25/2019 Layers of Fear
10/25/2019 Q.U.B.E. 2
10/17/2019 >observer_
10/17/2019 Alan Wake's American Nightmare
10/10/2019 Surviving Mars - Space Race
10/10/2019 Surviving Mars - Mysteries Resupply Pack
10/10/2019 Surviving Mars
10/4/2019 Minit
9/26/2019 Everything
9/26/2019 Metro: 2033 Redux
9/19/2019 Batman Arkham - Trilogy
9/15/2019 Unreal Engine
9/13/2019 Conarium
9/7/2019 ABZU
9/7/2019 The End is Nigh
8/29/2019 Inside
8/29/2019 Celeste
8/22/2019 Fez
8/15/2019 Mutant Year Zero
8/15/2019 Hyper Light Drifter
8/9/2019 GNOG
8/3/2019 Alan Wake
8/3/2019 For Honor Standard Edition
7/25/2019 Moonlighter
7/25/2019 This War of Mine
7/12/2019 Torchlight
7/12/2019 The Cycle Alpha
7/7/2019 Overcooked
6/28/2019 Last Day of June
6/20/2019 Rebel Galaxy
6/14/2019 Enter the Gungeon
6/8/2019 Kingdom New Lands
5/31/2019 City of Brass
5/23/2019 RiME
5/19/2019 Stories Untold
5/4/2019 World of Goo
4/19/2019 Transistor
4/5/2019 The Witness
3/22/2019 Oxenfree General Audience
3/7/2019 Slime Rancher
2/22/2019 Thimbleweed Park
2/9/2019 Axiom Verge
1/31/2019 Jackbox Party Pack
1/10/2019 What Remains of Edith Finch
12/29/2018 Super Meat Boy
12/15/2018 Subnautica
You can see a full list of every game given away so far (in alphabetical order) HERE