The latest free game to grab at the Epic Games Store is Borderlands: The Handsome Collection.
The collection will include Borderlands 2 and Borderlands: The Pre-Sequel and will be available for free until June 4 so grab it right away.
After that, another new game will be added to the freebie list, but thanks to a recent leak we already know that the next one is Ark Survival Evolved. So far the leak has proven to be true. The previous two games were Civilization VI and Grand Theft Auto V.
Source: Epic Games Store