BioShock: The Collection is the latest freebie on the Epic Games Store. Grab it anytime between now and June 2nd and BioShocks 1, 2 and Infinite are free to keep forever, including all the add-ons such as Minerva's Den and Burial At Sea.
If you're not familiar with BioShock, I envy you. They're decent first-person shooters with straight-forward character progression and simplified elements from immersive sims, such as stealth and hacking. They're also narratively exciting, with wild twists and surprises worthy of the visual splendour of their fantastical underwater and up-in-the-sky settings. I think they'd be fun to play for the first time today.
Unfortunately, they also contain political allegories, which prompted several years of the most tedious and embarrassing online discourse imaginable after their release. There's plenty to praise and criticise in all of the BioShock games, but they're Edward Scissorhands not War And Peace, and best approached as thrilling rollercoasters.
As someone who has played the main games, the collection is most interesting to me for the inclusion of the add-ons. Minerva's Den for BioShock 2 was made by some of the people who would later leave Irrational and create Gone Home, and the two-part Burial At Sea for BioShock Infinite received high praise at launch.
Head to Epic's game store the Epic Game Store to add BioShock: The Collection to your account. It's hours and hours of lush singleplayer gaming that would normally cost £40/$60.