Free PS4 games
PlayStation Plus:

    Rise of the Tomb Raider
    NBA 2K20
    Erica

Free Xbox One games

    Crackdown
    Crackdown 2
    Too Human

Xbox Live Gold:

    Dunk Lords
    Juju
    WRC 8 FIA World Rally Championship

Free Nintendo Switch games

    Jump Rope Challenge

Free PC games
Epic Games Store:

    Next Up Hero
    Sludge Life
    Tacoma

Twitch Prime:

    Art of Fighting 2
    Blazing Star
    Dark Devotion
    Dear Esther
    Dungeon Rushers
    Fatal Fury Special
    The King of Fighters 2000
    The King of Fighters 2002
    Melbits World
    NeuroVoider
    Kunai
    PictoQuest
    Pulstar
    Samurai Shodown II
    Turok 2: Seeds of Evil
    Vane

GOG:

    Akalabeth: World of Doom
    Alder's Blood Prologue
    Ascendant
    Beneath a Steel Sky
    Bio Menace
    Builders of Egypt: Prologue
    Cayne
    Delores: A Thimbleweed Park Mini-Adventure
    Doomdark's Revenge
    Eschalon: Book I
    Flight of the Amazon Queen
    Hello Neighbor Alpha Version
    Jill of the Jungle: The Complete Trilogy
    Legend of Keepers: Prologue
    The Lords of Midnight
    Lure of the Temptress
    Postal: Classic and Uncut
    Sang-Froid: Tales of Werewolves
    Shadow Warrior Classic Complete
    Stargunner
    Sunrider: Mask of Arcadius
    Teenagent
    Treasure Adventure Game
    Tyrian 2000
    Ultima 4: Quest of the Avatar
    Ultima Worlds of Adventure 2: Martian Dreams
    War Wind
    Worlds of Ultima: The Savage Empire

Uplay:

    Might & Magic Chess Royale
    Rabbids Coding

Itch.io:

    Becalm
    Death Ray Manta SE
    Fjords
    From Orbit
    The Restless
    The Things We Lost In The Flood

Free Mobile Games:
Free iOS Games

    Cytus II

Free Android Games

    Cytus II

Free Stadia Games
Stadia Pro

    Crayta: Premium Edition
    Destiny 2
    The Elder Scrolls Online
    Get Packed
    Grid
    Gylt
    Little Nightmares
    Monster Boy and the Cursed Kingdom
    Panzer Dragoon: Remake
    Power Rangers: Battle for the Grid
    PUBG
    Serious Sam Collection
    Spitlings
    Stacks on Stacks (on Stacks)
    SteamWorld Heist
    SteamWorld Dig 2
    SteamWorld Quest
    Superhot
    The Turing Test
    West of Loathing
    Zombie Army 4: Dead War