Product keys are used to add games to your library, but these keys are only produced when supplied by third parties or the software developers themselves. If you buy a game directly on Steam, you will never see a product key unless the game has its own key system separate from Steam. (Some games do this to lock in-game content that they don't want to manage through Steam's existing DLC system.) Once a game is in your Steam library, you can download it and play it. You need only have Steam running in order to play the game once it has been downloaded. Steam will also keep it up-to-date for you.
Thanks @Robert Maxwell -- the gaming world sure has made some amazing strides forward over the last 10 years. I've stayed away mostly because I'd get easily drawn in by the immersive worlds created and lose track of time. If you don't have a lot of familial obligations, it's scary how fast the free time can get sucked away by games.
If you have a Uplay account you can get World Of Conflict Complete Edition for free through the Uplay pc software for this week and next week Assassin's Creed Black Flag next week...
I'll probably never play it, but it's hard to argue with free. In the process of doing so I realised I also have Asscreed 3, Watch_Dogs & Blood Dragon on Uplay and entirely forgot they were there!
Sorry about the double post everyone but 'Grim Fandango Remastered' is now free on GOG for a limited time. If you've never played this before, now's your chance. All time classic Lucasarts adventure game! Also, if you already own the likes of Limbo, Baldur's Gate 1 & 2, the Homeworld games and a whole bunch of others on Steam, you can also claim them on GOG Connect. Why do that you ask? Well aside from it being wise to have as many of your games as possible on multiple download platforms in case one goes tits up (never say never!) GOG's copies are DRM free, making them much easier and safer to archive than it is on Steam.
GOG are at it again, this time it's 'King of Fighters 2002' that's up for free. Never heard of it myself, but it appears to be an old Neo Geo title. Also GOG Connect as a new selection of eleven games that you can transfer over DRM free from your Steam account. Oh and the original 'Dead Space' is free on Origin right now too.
Devil May Cry HD will be free on Twitch Prime soon. https://www.engadget.com/2018/02/13/devil-may-cry-free-on-twitch-prime/
One of my mates keeps recommending that (though his is console). Looks like it's time to give it a go
I got it in a steam sale several years back and personally I didn't get along with it very well; something about the FoV combined with the confined level design, the motion blur effects and slightly sluggish controls made me feel physically ill just playing. YMMV of course as I know that kind of thing doesn't affect everyone. Just giving a heads up for anyone who's had similar problems with other games to know what to expect with this one. Regardless, I'd still recommend it, as my personal difficulties with it aside it looks like a fun game to play, and the reviews speak for themselves. Plus of course it's always hard to argue with free.
GOG have a new game up for free: 'Dungeons II' which from the looks of it is a spiritual successor/remake of classic Dungeon Keeper.
Didn't know whether to put this in free games or deals but if you have prime this is good news. Free games via twitch prime is becoming a regular feature. https://www.engadget.com/2018/03/13/amazon-free-games-with-prime-twitch/
If you are a fan of the classic XCOM games you can currently get Xenonauts for free from GOG. It is limited time and will expire in around 31 hours from now.
'Warhammer 40,000: Space Marine' is free on Humble bundle for a limited time. This is one of those games in my Steam backlog that I actually got around to playing a while back and I feel confident in recommending it to anyone that enjoys fun third person action shooters and stomping hordes of filthy xeno scum into bloody mush for the glory of the Emperor!
Just on the off chance anyone here plays 'Star Wars: The Old Republic' and never subscribed, or never played but is curious: the first two expansions are free between now and Nov 1st. All you have to do is sign up for a F2P account (if you don't already have one) and redeem the code "REVANSFATE" to permanently unlock the expansions. You don't even have to have the game downloaded.
Heads up! Destiny 2 is free (just the base game) on Blizzard's site. Now to November 18th. Annnd I can't get it. Dammit Blizzard and their stupid SMS protection bs. Have to have a valid phone number... that's what I put in!