Continuing on from the previous post, let's look at an alternate scheme to increase interactivity in a game like Hearthstone. This scheme is used in several CCGs. I first encountered in the Babylon 5 CCG.
Essentially, the rounds become simultaneous. Each person gets a new mana crystal at the same time, and draws a card at the same time. Then one player takes an action to cast a spell or attack. That spell/action is resolved. Then the next player takes an action. You go back and forth until both players pass in a row. At that point the round ends, and a new round starts.
This isn't quite as responsive as Magic. But it makes the game closer to something like chess, where players alternate moves. If Anna does something that requires multiple actions, Betty has a chance to interrupt Anna.
Now, this scheme does have downsides. Needing to wait for the other person to pass can lead to stalling.
As well, this scheme sometimes devalues combinations of cards. For example, let's say Anna has a 4/4 on the board. Betty has a 1/1 and a Blessing of Kings (+4/+4) in her hand. Under the old rules, Betty could play her 1/1 and boost it to 5/5, putting her in a good position. Now if Betty plays the 1/1, Anna's 4/4 will immediately attack and kill it.
Building synergistic combinations of cards is a great part of the fun of CCGs. Schemes that promote more individually powerful cards at the expense of combinations can prove to be less fun.
This scheme also makes the decision tree a lot more complex, where you have to keep in mind your opponent's possible moves. It might very well be a strength of Hearthstone that each turn is self-contained, and allows a newer player to reason out her entire turn without interference from the other side.
Like, in current Hearthstone, if you play an incorrect sequence, it's fairly obvious when you recognize what the better sequence would be. But adding the other player's moves into the mix muddles that clarity.
Still, though, the scheme outlined above is more interactive than the current version of Hearthstone, and is also more suitable for computer play.