Last year's Dead Island 2 was a surprisingly solid entry in the open-world zombie series. After spending years in development purgatory, it was released to mixed reviews, and after months of exclusivity on the Epic Game Store, the game is coming to Steam this spring.

To celebrate the arrival of Dead Island 2 on the world's largest PC store, publisher Deep Silver is giving away an older title in the series: Dead Island Riptide Through tomorrow (February 15), get this 2013 action game for free! You can do so by visiting the game's Steam page. Just visit the game's Steam page and click the "Add to Account" button.

Once added to your library, this game is yours forever, so even if you don't have time to play it right now, get it. You can always come back to it later.

And if you're looking for more co-op play set in a zombie apocalypse, the original "Dead Island" is available on Steam for a whopping 85% off for $2.

Released in April 2013, the game was positioned as a spin-off of 2011's "Dead Island" and was created to hold players over until the release of the full-length "Dead Island 2" scheduled for 2015: Riptide" is truly "Dead Island" itself. But that's not a bad thing. [Even back in 2013, the graphics were muddy and bland: Riptide delivers that in spades.

In this follow-up to its predecessor, you choose one of a group of five survivors and, after enduring a shipwreck, venture to the fictional island of Palanai in search of resources and reusable goods to help you survive. Of course, the tropical paradise is teeming with brain-devouring undead zombies, and along the way they must use every weapon they can find to fight them off.

Dead Island Riptide emphasizes melee combat. While firearms and projectile weapons can be found, ammunition is very limited. You will have to use everything from baseball bats to large pieces of wood to make the zombies bleed. You can even create special weapons to inflict even more damage.

While you won't be able to linger long on the cheap thrills of single player, Dead Island: Riptide is a lot more fun when played with a friend (or three). The entire game can be played cooperatively with up to four players, and since the island of Paranai is reasonably large, you can do a lot of side-opinions in the middle of nowhere.

Steam also distributes a Definitive Edition of Dead Island: Steam also distributes a Definitive Edition of Dead Island: Riptide, which includes all of the game's DLC! In addition, the visuals have been improved over the original version. However, even with these adjustments, this should not be mistaken for a brand new game.

It would be a bit of an exaggeration to declare Dead Island an underrated masterpiece: Riptide is an underrated gem, but for the low price of $0, it is a very worthy addition to your Steam library and the perfect way to pass the time. Grab a few friends and join the zombie slaying.