Oddworld: Abe's Oddysee is one of the strangest games you will ever lay eyes on and it just happens to be free on Steam and GOG for the next day or so. You get to keep the classic title if you rush over to one of these platforms and just add it to your library for zero money.
Oddworld: Abe's Oddysee released back in 1997 or roughly 20 years ago for the original PlayStation and PC. The title has spawned a number of sequels, and the first outing of the franchise is now free if you hurry and grab it off Steam or GOG in the next 24 hours or so.
A fair warning, Abe's Oddysee is punishingly hard by today's standards, and in spite of ageing very well the puzzle platformer may be more than a contemporary player's digestive tract can handle. It should also be considered that the game's save system was criticised as being somewhat unfair even back when it was released.
"Selected by the fickle finger of fate, Abe, floor-waxer first class for RuptureFarms, was catapulted into a life of adventure when he overheard plans by his boss, Molluck the Glukko, to turn Abe and his fellow Mudokons into Tasty Treats as part of a last-ditch effort to rescue Molluck's failing meat-packing empire" is the promo blurb explaining the game's initial story bit.
The entirety of the Oddworld franchise is on sale for the next few days accompanying the free promo game as well, so if you like what you see this is as good a chance as any to get the entire series for a little more than pocket change.