It could be purposeful as some developers will give out copies of their newer or older games like this. Although usually it is another copy of the same game which goes directly to your inventory.

Or it could be a big oopsie on their part. Developers can rescind keys, but usually they don't do that, so enjoy the free game. :P

Ubisoft's doing a 30 Days of Giveaways starting today and running up to Dec 23rd. Most of it is stuff like wallpapers, gifs etc, but as far as free games go, here are the highlights:

Today: Rayman classic on mobile
Dec 7: Assassin's Creed 3 (PC)
Dec 15: Prince of Persia (PC)
Dec 16: Rayman Legends (PC)
Dec 17: Splinter Cell (PC)
Dec 18: The Crew (PC)

Neverwinter Nights: Diamond is free on GOG for a couple of days: https://www.gog.com/game/neverwinter_nights_diamond_edition

Between Me and the Night is currently free over at indiegala

I had a bit of trouble getting their site to cooperate this morning, but Assassin's Creed III is free starting today for Uplay on Ubi 30: https://club.ubisoft.com/en-US/ubi30.

Lost Odyssey for the Xbox 360 and backwards compatible with the Xbone is "free" on the Xbox Store, though you may need Xbox Live Gold to "buy" it.

It will be available through the 31st.

I am not an Xbox Live Gold subscriber and was able to get Lost Odyssey. :D The only catch appears to be that you need a payment method on file with your MS account to download this - even though it's free.

Apparently the Ubisoft games listed by Dhobo above aren't new games being given out, but just part of a special weekend to claim any of the Ubi 30 games you missed.

Guess they didn't get much traffic claiming the games on the individual days they were being given out? Either way, you can snag all 7 at once from here https://club.ubisoft.com/en-US/ubi30 until the weekend is out.

All on uPlay, in case it wasn't obvious.

Awesome. I was someone too lazy to pick up each game as it popped up. :P

Not so much free game as free credit, I turned on my PS4 today and had a message waiting. It was from Sony and it was a voucher for $10 credit on the PSN store.

I ended up getting Dragon Age Inquisition (no DLC, but it is the deluxe version) on sale for $7.99 in the Holiday Sale and a Rock Band song ("Hook" by Blues Traveler) for $1.99 normal price.

So not a bad Christmas gift AT ALL out of nowhere.

EDIT: Apparently it's for new purchasers of the PS4 Pro or Slim models (the latter is me).
So spending $30 more than my original plan for a PS4 has gotten me a new one instead of a refurbished one, a Slim model (which typically has all the bugs worked out) rather than the original model, Uncharted 4, Dragon Age: Inquisition and Hook for Rock Band. Not a bad deal AT ALL.

http://www.playstationlifestyle.net/2016/12/06/looks-like-sony-is-sending-more-10-psn-credit-to-new-ps4-owners/

Mass Effect 2 standard edition is supposedly free on Origin, though I don't appear to see that deal.

GRID is currently free over at Humble

Ok, so now Mass Effect 2 is free on Origin as part of their On the House thing.

Someone needs to talk Origin into giving away Mass Effect 3 as well.

DiRT Showdown free over at Humble: https://www.humblebundle.com/store/dirt-showdown-free-game

For 48 hours only

Niiiiice! Everyone should snag a copy since it's a great multiplayer game :D

Alien Shooter 2: Reloaded is free over at IndieGala

Requires e-mail and doesn't always work right away. You have to wait 5 minutes between tries. I got it on the second.

The original X-COM: UFO Defense (with the hyphen) is available for free at Humble Store until 10AM on Wednesday Pacific Time!

https://www.humblebundle.com/store/xcom-ufo-defense-free-game?hmb_campaign=free_xcom_ufodefense_2017&hmb_source=bundle_page&hmb_medium=banner

Constructor is free until Feb 1st over at GoG

Robowars is currently free over at IndieGala

Star Citizen has a free trial type thing until February 19

oh ya i almost forgot if here's a referral code STAR-N43G-RWXK. If you use when you make an account you get 5,000 ingame credits, and if you buy the game i get an ingame weapon.

The 2006 RPG Eschalon: Book 1 is free on GOG right now: https://www.gog.com/game/eschalon_book_i

A King's Tale: Final Fantasy XV is free on PS4/XB1 now. It was previously part of the preorder for Final Fantasy XV.

PS4: https://store.playstation.com/#!/en-ca/games/a-king's-tale-final-fantasy-xv/cid=UP0082-CUSA05932_00-AKINGSTALEFFXV00
Xbox One: https://www.microsoft.com/en-us/store/p/a-kings-tale-final-fantasy-xv/bw0d9lh9gg6d?tduid=(2de413d97af78fd5eabaa649cd81c6c1)(240780)(2316686)(CAqD7bLWUPI-uejkR2L0vVy2GKTcRHZ21Q)()

I presume this is DLC for Final Fantasy XV?