Valve's Dota themed card game Artifact has now well and truly failed, as they've now stopped the 2.0 redevelopment which is now named Artifact Foundry with the original as Artifact Classic and both now free to play.
In a post titled "The Future of Artifact", Valve mentioned how the player count fell off dramatically and it was pretty much dead shortly after being released. Even though the big 2.0 revamp was far along in development, they've now formally and totally shelved it as they "haven't managed to get the active player numbers to a level that justifies further development at this time".
Neither game has micro-transactions, they're both properly free now. However, previous purchases entitle players to Collectors Edition cards. These special cards can be bought and sold on the Steam Market, players who purchased it originally will also be able to earn these cards by playing, free players joining now will not.
There are some major differences between them like how you play across the board. The original, now Artifact Classic you would play each lane across the game in a sequence of turns, but Artifact Foundry has a more simplified take on it where you have the whole board and play in any lane at a time. Each version also has different game modes available.
For a full run-down of the differences between Artifact Classic and Artifact Foundry, see this post.
Both versions are now on the combined Steam store page.
Personally, I am sad to see this. Artifact had fun and engaging gameplay, along with great visuals but it was the monetization model that ultimately killed it. The idea that you had to pay for it, then pay more to play more of it across some of the modes was not good. Perhaps in time now it's free, it might see a reasonable rise in the player count. For now though, Valve has no further plans to update either version.