First:

OpenDev for December starts at:

 December 15th at 16:00 CET (10:00 EST, 7:00 PST) to December 28th at 16:00 CET

So it starts tomorrow.

Second:

The instructions are:

So how can you play the Humankind Lucy OpenDev? Just follow these simple steps:

So how can you play the Humankind Lucy OpenDev? Just follow these simple steps:

1. Make sure that HUMANKIND™ is in your Steam library.
   1. If you have pre-purchased the Digital Deluxe Edition on Steam, it should be there already 
   2. If you have purchased a Steam key from another retailer, you must Redeem the key on Steam first before proceeding to the next step 
2. Visit GAMES2GETHER
   1. If you already have an account, go ahead and login 
   2. If you do not have an account, please create one 
3. Steam connect your G2G account on the rewards page here. If you have already connected your account in the past, you may need to re-sync 
4. Once the OpenDev begins on the 15th, click on the “Lucy OpenDev” reward and hit Redeem. 
5. Go back to your Steam library, and Humankind – OpenDev should appear there automatically

Specifically Step 4 and Step 5.

Meaning that you need to check your Games2Gether account on the 15th in order to see if you recieved the "Lucy Opendev" reward. After which you hit redeem and then go back to your steam library to see if "Humankind - Opendev" (Different game from the Actual Humankind) appears for you. This is similar to what they did for the Summer 2020 OPendev.

So, I just got the badge here - after trying for an hour. Restarted STEAM and still nothing.

Finally, after several reboots the invite came on this site. So, what was the badge all about? Anyway, it is now installing.

You have to sync it and link it with steam, make sure you don;t have any javascript blockers.

If you prepurchased the game on Decemeber 15th will it work or did you need to do it earlier? I prepurchased it earlier today and still cannot access the Lucy open dev

I can't access it either. Pre-ordered it on Steam. Restarted the app, twice now and still nothing.

Search for Humankind: Opendev in Steams store, download and play.

Daalon wrote:

Search for Humankind: Opendev in Steams store, download and play.

Yes, having the same idea and it works. 

I buy pre-purchase of Humankind today, but still havent OpenDev Lucy in my list of games. If i open in Steam page of OpenDev Lucy.. it offer me to buy pre-purchase (but im already buy lol) instead of installing the game. Wtf? Is this a trick?

Buy game so it on steam then sync account here and then switch away from and then back to the reward page until the Humankind lucy opendev pop ups as a claimable game at the top of the page. Select it and redeem it to steam (if it fails just click redeem again) and now you can launch and play.