Okay, Puzzle Strike is on Steam, so let me do a PC port of good card games round up here, just focusing on a few.
Puzzle Strike is by David "My only contribution to your life is ruining every video game forum thread in the late 90s early 00s by writing Play To Win." Sirlin. It's a versus mode deck builder themed after Puzzle Fighter and is somewhere close to brilliant. Sirlin likes competitive games and he put a LOT of game design thought into this. The result is a lightning quick 1v1 deckbuilder* where you really have to consider your strategy against your character's unique cards, the bank, and what your opponent is likely to do. Sirlin thought about this harder than you ever will and sells like a 100+ page strategy guide for this game, and he gives away for free a chart showing where characters fit on the economy, attack, and defense continuum. This is a simple yet incredibly deep game. It's a bit different than what you expect though so you may want to try the free to play version online, which has rotating free characters. Buying the game on Steam essentially gets you the entire set of characters from the core set. You don't need the expansion. I highly recommend at least trying this out. AI is decent if you don't/can't find anyone online.
Ascension has a bad review score on Steam and it doesn't deserve it. You all played this on Iphone probably but the Steam version has every expansion baked into the box. Ascension is a simpler, more straightforward deckbuilder. Still 1v1 focused. Here you just collect cash and power to fight monsters and buy cards that show up in the center row. It's very random but the engines and powers available are interesting and you get EVERY expansion, each of which change up the game immensely, so you have an enormous amount of ways to play, including playing with every expansion thrown together if you are insane. Nowhere close to as intense or multi-dimensional as Puzzle Strike. It's clearly a port of the Iphone app so the MP interface makes no sense except for people who want to play a turn, put it in their pocket, and get buzzed when it's their turn again. But the negative reviews are wrong, it plays very well, performance and mechanics wise.
Sentinels of the Multiverse added online coop now. It's a cooperative superheroes game where each player has a prebuilt deck (no deckbuilding this time.) that is built around that superhero's style (The Batman expy drops loads of equipment with great damage on the table, the Flash expy has powerful nukes that trigger if she has a lot of her weaker cards in her discard pile, there's a bard character who plays instruments and songs to create elaborate buff chains...) and you are facing off against a villain boss fight, which is completely automated, dictated by the rules of their deck. The game is quite fun but about half of the content in the game is really bad. Certain bosses are just mindless DPS races, one boss literally has a card that destroys cards you played each turn, then you have to destroy a bunch of your own cards to get rid of it, but then she has a bunch of cards in her deck that fish that out of the trash so you will NEVER have cards on the table. But when the game isn't a mess, it is really quite fun. Perfectly playable solo if you want to play all the heroes but can be played online if you like. No AI play because there is no human working the opposition. It's full co-op.
*A deck builder is a game where you have a deck of crappy cards, most of them cash. You buy new cards with the cash each turn and shuffle them into your deck, so you are building your engine with every play, better still if you can get cards that let you remove cards from your deck. Do you go for the removal? Big money to buy the power cards? Do you go for a chain engine to play your whole deck each turn? Depends on what the game offers.
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