Truisms reiterate something that's already blatantly obvious, a rhetorical device employed when a truth needs to be made evident through circular reasoning. In Trism the reasoning is triangular, but that doesn't hold it back from becoming the iPhone's first truism: this must-have puzzler is a must-buy for anyone with an iPhone.

The goal of Trism is simple: eliminate triangles by grouping at least three of the same color. Similarities to Bejeweled can't be denied, as the game clearly comes to iPhone inspired by PopCap's modern classic. Any parallels drawn between the two games are cursory, though, as Trism breaks out on its own with an array of innovative twists.

Individual triangles, which are called 'trisms', can't be moved independently; instead, you move entire lines of trisms to clear like-colored groups from the board. Trism lines can be moved horizontally, vertically, and diagonally at two different angles. For example, if you wanted to connect a single yellow trism with a nearby pair of yellows, you would touch the sole trism and slide that row until one of its sides met with the pair of yellow trisms. When you lock that single yellow trism into position, you're also dragging whatever other trisms are on that same line. In other words, you're effectively shuffling the board.

As soon as you clear a group of trisms from the board, new ones descend to fill the empty space. Here's where Trism distinguishes itself from other puzzle games: the position in which you hold the iPhone determines how trisms fall into the empty spaces on the board. Trisms always fall from top of the board, which is relative to how you hold the handset. Turn your iPhone on its left side and trisms will descend from the opposite side, now the relative top of the board.

Naturally, this opens up the possibility for insane combos triggered by trisms tilted into all kinds of positions. Clear a trio of trisms and you can tilt your iPhone in order to direct descending trisms into another group, then readjust for a second tilt-based combo, and so on. Millions of points can be earned through skillful tilting of your iPhone in a matter of seconds.

Calling this a minor evolution on the Bejeweled formula is tantamount to a cheeky reference to the Atlantic as a pond. In truth, it's huge. Trism not only manages to innovate in an over-crowded genre, but also provide an experience on iPhone that simply cannot be duplicated on any other current platform. This makes it a must-play, a platform-defining experience that combines ease of play with innovation.

Trism earns its score not solely for its inventive gameplay, but also the variety offered amongst three discrete modes, achievement system, and online rankings. Infinism mode is the default game, having you clear trisms to earn a high score. Terminism, meanwhile, adds the element of time to the mix, forcing you to make moves before time counts down. It's obviously a more intense variation on the core game.

Syllogism differs completely from the previous modes, focusing entirely on tilt-driven puzzles. Clearing trisms from these stages requires tilting your iPhone – you're not allowed to move pieces using the touchscreen. Along with both Infinism and Terminism modes, special achievements can be unlocked and high scores posted online when playing through Syllogism-flavoured stages.

For a launch title, Trism far exceeds expectations with highly innovative gameplay and a full set of features. Easy to play, yet immensely challenging and deep, it will undoubtedly hold its place as an essential iPhone puzzle game long after the excitement of the App Store launch dissipates.

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