I remember with fondness the days I spent trying to master Tetris. This was my first addiction to a puzzle game, but definitely not my last. I think the appeal of puzzle games is the fact that they are generally quite simple to play, yet ultimately challenging to master. Consider, for example, one of the world's latest trends: Sudoku. The basics of the puzzle boil down to filling a bunch of squares with the numbers one through nine, yet some Sudoku boards can easily take an hour or more to complete.

Over the past couple of months, I've had the privilege of playing five challenging puzzle games. They are not only very different games, they are all very addictive!

Armadillo Gold Rush (A)

$9.95; Touch and non-touch screen; Free demos

Developer and purchase: appabove.com

It only took a few levels for me to fall in love with this game. You play the part of an armadillo trying to horde a collection of gold coins. In order to clear each level you must gather all the coins on that level, and the only way to do this is to roll over them. The challenge comes in the fact that you cannot stop rolling until something stops you.

Fortunately, there are plenty of objects that can stop you; unfortunately, not all of them are good. Items like hedges and rocks will halt your progress and allow you to choose another direction to move in. Objects like springs and fans will automatically change your direction. Spikes, canyons, and some other objects will stop you in your tracks permanently. Thankfully, you are not limited by a set number of lives in this game, so if there's a level that's particularly difficult, just keep trying until you get it right.

With a few exceptions, the level design in this game is very well done. Of course, the levels aren't always easy to appreciate until they are completed, but to me that's a sign of excellent layout. Also, while there are a couple of occasions where a level doesn't seem to fit in with its neighbors, there's generally a nice gradual increase in the difficulty of the game. This is something you don't find in many games these days.

The graphics are a bit small, but everything looks good and is nicely detailed. The animation is pretty decent as well. The sound effects are okay, but they often seem to just fade away for a while. The music is nice, but only plays during the menus. Finally, although the game is available for both touch and non-touch screen devices, I could not get it to work properly on my non-touch screen smartphone. The developer is aware of the problem and is working on a fix.

Overall, Armadillo Gold Rush has a professional feel to it, and while the conceptual elements have been borrowed from other games, everything has been assembled to provide a unique take on the puzzle genre. This is definitely one game that die-hard puzzle fans (and potentially more intense casual gamers) shouldn't be without.

Crazy Spot (A-)

$12.95; Touch and non-touch screen; Free demos

Developer and purchase: umobilegame.com

When I was a kid I used to enjoy picture puzzles. These display two nearly identical pictures and challenge you to find the differences. Finding them was a challenge—unless someone else had worked the puzzle before you and had already circled the variances. U Mobile Game has brought this simple cranial diversion to Windows Mobile devices in the form of Crazy Spot.

Crazy Spot presents you with a series of near-identical pictures with five variances. Your job is to tap on or select the variances, in either one of the pictures, before the timer runs out. Be sure to select the variance where it is more obvious. For example, if an object is missing from one picture, find it in the other picture and select it there.