@ RaceBandit
The 5x5 area effect is a good idea, and variations of that have been suggested to me before. If I were to make some major rule modifications I would definitely play around with the range of the Convert All card. One thing I've learned from making a game like this is it has been impossible to make everyone happy with one set of rules. If there ever is a version 2, it will have a customize effects page so players can just turn off what they don't like.
If the countdown firing too quickly is such an annoyance I can easily change it as it's one line of code. I believe it's currently set to start off at 10 seconds in the early levels and max out at 1 second in the later levels. How about I scale that back to 15-5 seconds instead? I'll release an update tonight.
Losing in one turn is possible, but it doesn't happen too often once the player knows the computer can use the Convert All card in the following turn to end the game. It is however an unfortunate side effect of trying to make a game that finishes quickly.
It's true that the "Convert All" card can seem overpowered and it was suggested to me to scale back it's power before. But there were two reasons that made me keep it the way it was. First, if a round goes on for a few turns the destroyed tiles will build up, making that card less powerful and next to useless as a round drags on. Second, the horizontal and vertical cards should be used to counter the effect of the "Convert All" card by intersecting the colored areas thereby preventing a win in one shot. ie Don't have wide areas of the same color unless you're preparing to win that turn.
For the timer making the game unplayable in the later rounds, yup, I did that on purpose. If I didn't, people would be complaining it gets boring after 10 rounds. It forces the game to end since there is no final boss round.
 "Convert This"){kind=icon}