For a few years now one of the greatest enemies to American business productivity was a web game called "Bejewelled". The simple, yet compelling and addictive gameplay made the game like Lay's potato chips... you can't play just once.
Zoo Keeper owes it's basic gameplay to Bejewelled. A grid of animal shapes, you can swap postions of any two adjacent to form a group of three matching animals which then vanish, letting the critters above them settle down into the empty spots. Additional chains of 3 can then happen scoring higher points.
The main differences are the little touches that make Zoo Keeper a superior development of the old formula. Rather than ending the game when there are no more possible moves, as in Bejewelled, ZK reshuffles the tiles and you play on. The animals are well drawn and well animated. There is a quota system for each level in the basic game, so you must 'capture', make a chain of 3 or more, a certain number of each type of animal to advance. The animals make sour faces if you haven't gotten enough of their type so you get a constant input without looking at the numbers in the upper screen. A subtle touch that really makes the game.
It plays fine using the D-Pad, but like all the various Bejewelled clones on Palm OS and Pocket PC machine (I have several of each) using the stylus on the touch screen makes play much easier and much faster. You can be making more moves while the previous chains are still resolving. Yes, ZK -could- have been made into a GBA game very easily, but the top screen and touch screen make a big difference in both presentation and controls.
The additional game modes are also very good. Tokoton mode sets the animal quota for each type to 100 making for marathon sessions. Time Attack limits play to 6 minutes for the opposite. The mission mode sets 10 special challenges such as making only vertical chains, or capturing only a certain creature. 2 player is a hoot. Just like many other puzzle type games, each player plays his own game board but each success makes the other guy's task harder. Kinda takes me back to Dr. Robotnik's Mean Bean Machine on Sega Genesis (and again on new consoles in the Sonic Classics games).
My only criticism would be that this is the 1st Nintendo DS title which isn't a 'license' title (such as Tiger Woods Golf or Madden NFL)to be priced at $39.99 The $29.99 price point of Ridge Racer, Asphalt, Mario 64 etc... is much more genial. I suspect that vendors are going to get their noses bloodied trying to get 40 clams for any NDS title after the Sony PSP debuts in America, the disparity in content is too telling.
Having said that though, Zoo Keeper is a great deal of fun and will charm even non-video gamers into playing it (read girlfriends) and having a good time.