Gameplay:
It doesn't use a resource system like MTG or Marvel/DC Vs. Rather, each card has a "SIZE" value associated with it. One is only allowed to have up to "SIZE 10" on the field at any one time. So - if you play two unit cards with a very large SIZE value - then you won't be able to play other spell cards or bring anything else onto the field until they die.
Unit cards have a TCG standard "Attack / Defense / Health" setup. After you complete you turn, the attacking and defending happens automatically as the AI decides what cards your cards attack. This is likely the weakest point of the game. Without that direct control, it makes the game much more random and simpler (thus far in my opinion).
There appears to be around ~70 cards for each faction currently in the game. Deck size is 30 cards with most cards allowing a limit of 3 (some are limit 1).
Free To Play Aspect:
You can earn materials by playing the dungeon (ie. against the AI) that I know of so far. Using these, I believe it is possible to craft ever card, but it does seem like it might take awhile. Many cards you can just craft from these materials but some require 4-5 crafted cards already to make them (which would likely take around 25 matches, I'd guess).
So - basically similar to League of Legends. Possible to get everything for free theoretically but the majority of players won't have time due to the high costs of "free".
There is also a way to "train" cards as well that apparently makes them more powerful. I haven't really tried out this feature yet to comment on it.
Other Stuff:
The "Quest" button basically acts as the tutorial. Completing the boring stuff it asks one to do gives a bunch of free stuff. After that there is a beginner dungeon that gives gameplay tips.
Will edit in more as I think of it.
Link to the game:
http://www.swordgirlsonline.com/
TL Player List:
Need a TL channel as well as the game is broken into 5 shards. Any suggestions / preferences?
+ Show Spoiler +
TL UserName ------ Sword Girls Name ------ Faction
[-Bluewolf-] ------ Bluewolf -------- Crux