Before you jump down my throat, no, Dominion wasn't the first tabletop game with deckbuilding in it, with predecessors like StarCraft: The Board Game. Dominion was, however, the first to build an entire game around the mechanic, giving birth to the genre that would hop to PC with Dream Quest, Slay the Spire, Monster Train, and so on.
Dominion was unavoidable at board game night in 2008, with everyone wanting to pretend to be medieval landlords who could buy up markets and villages and occasionally witches in the tireless hunt for the thing every board gamer wants—victory points. Digital versions followed, in the form of apps and a browser-based Dominion you can still play. What makes this version different is that the AI opponent is powered by neural networks, and it certainly seems competent. It beat me on the easiest difficulty a couple of times, though to be fair I was still trying to remember how to play since it turns out 2008 was actually a while ago and I've forgotten all the combos.
What's nice about this version of Dominion is that it's fast. With no unpacking or shuffling or convincing your friends to spend time in your company it's extremely zippy. It's actually a bit too fast. Your opponent's cards fly around before you've clocked what they are, even with the animation speed set to slow. Are they using Moats to block my Curses? No idea, guess I'll find out at the end. (They were, I lost.)
To squeeze in one more complaint about the interface, it's a shame the cards don't embiggen on mouseover. To see anything beyond the card art, which is nothing to write home about, you have to right-click on them. But I suspect the sticking point for a lot of people will be the DLC.
While the base game is free, the expansions obviously aren't. If you want the extra cards added by the Intrigue expansion that's a fairly reasonable $US5, while sets like Hinterlands and Dark Ages cost $US11 a pop. There are currently 23 expansions available, with more likely on the way. It's a completionist's nightmare.
You don't need any of them to play Dominion, of course, and honestly all of them would be too much to keep track of. If you want to experience or re-experience the hot new board game trend of 2008 on Steam this version will let you do exactly that, either on your own or online.