You can claim a free Animated Avatar, Avatar Frame and Animated Sticker on Steam to celebrate Deckbuilders Fest:
https://store.steampowered.com/points/shop/app/2842700
Nomads of Driftland: The Forgotten Passage is free on GOG until 3/8 at 3:00 am EST:
https://www.gog.com/en/game/nomads_of_driftland_the_forgotten_passage
Ultimate Zombie Defense is free on Steam until 2/11 at 1:00 pm EST so act fast! That's only 2 hours from now!
https://store.steampowered.com/app/1035510/Ultimate_Zombie_Defense/