My favorite holiday tradition is pressing "get", "Claim," "Add to Library" on the various givaways and then forgetting about the games for months to years as I have so many games I haven't even looked at, let alone installed. I almost get a larger sense of accomplishment claiming the games than playing them.
A reliable leaker hints at Hell Let Loose as the final free game in Epic Games Store's Holiday Sale. The detailed clues align pretty well with this tactical WWII shooter being the 16th giveaway choice.