Normally sold for £19.99 and £24.99 respectively, those are downloadable right now, live as of 8am PDT / 11am EDT / 4pm BST / 5pm CEST. Like always, you can claim it for a full week and come August 5th, that'll be replaced by A Plague Tale: Innocence and Speed Brawl. All you've got to do is click "purchase", pay nothing, and it's yours to keep.
Mothergunship And Train Sim World 2 Are This Week's Epic Store Freebies
For the interested, Mothergunship is a bullet-hell FPS which involves crafting your guns, fighting huge bosses and defeating "a robotic alien armada that conquered Earth". Describing gameplay as facing "overwhelming odds in brutal, non-stop combats", you'll need to adapt to survive.
As for Train Sim World 2, Dovetail Games offer this outline:
The evolution of train simulation! Master iconic locomotives on high-speed services, long freight hauls or precise commuter traffic, and get creative with customisation tools in this advanced sequel. Climb into the cab in Train Sim World 2.