If you're an aficionado of math puzzles, you may have heard of the famous Magic Square brain-bender, which was apparently invented in China about five millennia ago. A Magic Square is a square grid, usually three by three or four by four, which you fill up with consecutive numbers in such a way that the sum of each row, column, and diagonal is the same. Tic-a-Tac 21, from Mobliss, is a brilliant adaptation of the puzzle for mobile phones that uses playing cards in place of integers. This game uses a facile framework--a three-by-three tic-tac-toe grid--to generate a huge variety of difficult brainteasers. Once you pick up this compelling puzzle mechanic, it's not easy to put down.
There are three different ways to play Tic-a-Tac 21, but they're all generated off the same basic idea. You're given a certain number of playing cards to place on your grid, from which you try to generate as many blackjack-style 21s as possible. If you come up with the perfect layout, you'll have eight 21s (along the three rows, three columns, and two diagonals), and you'll score mondo bonus points. However, if you should bust out (go over 21) along any of your scoring lines, you'll get a donut for that section of the board. Scores under 21 are tallied at the end of each timed round at five points below their indicated value--so a 20 counts as 15 points--while 21s count for a full 21 points, with bonuses for each additional 21. Also, in order to progress to the next round, you must produce at least one 21 on the board.
In the bread-and-butter solo mode, you'll progress through one puzzle after another until you flame out, generating a high score. There are four difficulty levels here, which really change the game significantly by ratcheting down the time limit and the number of cards you have to work with. You get 19 cards on the easy level, giving you lots of tactical choices, but only the bare nine on expert. Furthermore, you're not allowed to scroll through the cards on expert level; you must place them in the order they're given, which raises the difficulty to astronomical levels. There's something in solo mode for everyone from 9-year-olds to Stephen Hawking.
The surprising depth of the puzzle designs will start to reveal itself over time, as the game deals you an assortment of low, high, and medium cards. As you might imagine, aces, which can count as either one or 11, are particularly important, as is the board's center square. The time limit doesn't let you work everything out on scratch paper, either, so you are forced to develop workable strategies for various general situations.
The other two modes are interesting, too. In duel mode, you play an actual hand of blackjack against the dealer for the right to place a card from your hand on the board. The card's marked either X or O, and you must have at least one of your symbols in a sequence that adds up to 21 to progress to the next round. Timed mode requires you to make a certain number of 21s in a given time to progress to the next round, starting with one 21 in two minutes and working upward. Your bonus ticks away every five seconds. Tic-a-Tac 21 uses Sprint's Game Lobby to compare scores for this mode online.
Tic-a-Tac 21 looks really good for a puzzle game. On Sprint's LG MM-525, the interface is crisp and functional, and there's no extraneous art to bother with. The timer uses a slowly draining meter that's easy to read at a glance. The sound is good, too, mostly because it never stands out.
Tic-a-Tic 21 is a great puzzle game that's very well suited to mobile. Most of the competition lacks this game's variety of game modes and highly scalable difficulty; plus, the Magic Square's been around for a good long while for a reason--it's really interesting! We highly recommend downloading it.
