There isn't much to the rules of Poison. In fact, all of the rules fit onto one iPhone screen (right). For people who can't read the image, here's how the game works.
Each player is dealt a hand of cards and must, on their turn, play a card into one of three piles. Cards of the same suit need to go together, poison cards can go anywhere. If the sum of any pile (depicted as little cauldrons) gets to 14 or more, the player who broke the 13 barrier needs to collect all of the cards in that cauldron except the one he just played into his score pile. You go until everyone is out of cards and then count up your score. The goal is to get the fewest number of points.
Since this is a Knizia game, the fact that the scoring round has a bit of a twist isn't a surprise. Whoever collected the most cards of one of the colors gets to discard all of those cards. This is really what makes the game worth playing, since it gives you a chance to score low even if you get stuck with a bunch of cards early in the game. Also, there are interesting decisions to make about filling a cauldron with lots of low-point cards or one or two big cards, depending on what you have in your hand and what you're trying to collect. Each card you end up with after any discarding scores you one point, except the poison potion cards. These are deadly to your score as they are each worth two points at the end of the round. You play a number of rounds equal to the number of players in the game (between three and six IRL and four and six on your iPhone) and that's that.
Playing the game with physical cards around a table, you get to see how many cards a player has collected, but not how many points in each color he or she has. The iPhone version does show your opponents' point totals, and therefore makes it that much easier to push your luck and try and take the majority of one color or to stick a particular opponent with a poison card. If you like to say "take that!" to a real person, you'll need to search out the real card version. The app is single-player only. Pass ʻn' Play would've been nice, and this brings us to our first in a whole list of improvements that we would like to see.
The level of addition needed to play Poison isn't exactly difficult. For most people, it'll actually be quite easy. Still, considering that digital versions of board game apps have the potential to add interesting flourishes, the lack of running totals next to each cauldron/pile feels like neglect.
They are hard to see, but there are two important buttons near the bottom of the game screen, above your hand of cards. On the left is the quit/back to menu button. On the right is an info button that toggles between showing you the number of points an opponent has (like this and at right) and the name and total score of that opponent (like this). Why not show both at once? We can see it getting crowded when playing the six-player version, so we'll cut Griptonite a bit of slack on this item.
One thing that's a lot less forgivable is that that you can't listen to music while playing the game. Yon can mute the game's music, but iTunes won't fill the void if you do. Is there something incredibly difficult about coding the app to allow iTunes to keep playing when the game is running that's preventing Griptonite from implementing this option? If so, why can other developers figure it out? Players have been complaining about this since the app was released last fall and it still hasn't been updated.
Another annoyance is that there is no way to change the AI's ability level. The standard AI plays well enough to make the game interesting, but a beginner level for the first game or two would be a nice touch. Also, some players have complained that it appears the AI opponents know what cards you're holding (which would be cheating in the real world) and play accordingly. Not fun, especially if you're into the whole winning thing.
Even with all of these shortcomings, Poison is a fun little app. It doesn't beat playing around a table with friends, but what should we expect from a three dollar mini app?