Tidalis takes the Tetris genre of games and rips it apart. Tidalis is basically Tetris on steroids.
Like Tetris, multi-colored blocks will fall down your screen at regular intervals. If you match up the blocks correctly they'll be cleared, but if too many blocks stack up (to the top of your screen) you lose. But that is where the similarity ends.
In Tidalis you create "streams" to clear your blocks, and with clever positioning it's possible to use streams to clear blocks all across the play area. As blocks are cleared more streams can be created allowing you to create combos that give you extra points. It's really cool to plan out a chain reaction and see it pay off!
Also, there are about two dozen special blocks to spice up gameplay. Some of these are generally helpful, such as a "quad repeater" -- if one stream goes into the repeater, four come out, meaning you can get some really nice chains or combos going. But some special blocks are generally unhelpful, such as an "idol" block, that will halve the score of any chain that touches it. Usually there are only 1 or 2 special blocks used per level, and you're given a briefing on exactly what they do before the level starts. This is good as it prevents players from getting overwhelmed from the sheer variety possible.
Speaking of variety, there are a ton of different victory conditions to keep things fresh. Remember how I said that quad repeater blocks are generally good? Well how about a level with quad repeaters where the victory condition is to score the smallest chains possible, and the loss condition is to score too many large chains? In that level you'd actually want your streams to avoid the quad repeaters to keep your chains from getting too big!
There are also items that you can use in some levels, for example one item will remove several blocks from the play area and put them in your inventory, allowing you to re-arrange them at your leisure.
There are also many different game modes. For example in "Graviton" game mode your streams are affected by gravity, meaning they do not go up as far, but they go down much further.
Fortunately there are several tutorials for this game, and a Custom Game mode where you can experiment with all the multitude of options.
There is also a Versus mode where you play against other human players, and a Co-operative mode where you work with other human players to beat a level! There is a level editor included so you can create your own levels from scratch!
Finally, there is Adventure mode, which is the main single-player campaign. Whoever heard of a Tetris-genre puzzle game having a single-player campaign with a storyline??? I think that was a pretty nice treat. There are 115 levels in the campaign, with another 100+ optional "Brainteaser" levels. If you get stuck on a level you have the option to skip it, but I'm pleased to say I was able to make it through the whole campaign without having to skip any levels, so the difficulty level was about right. The Brainteaser levels are quite different from normal levels. In Brainteaser mode no blocks fall from the top of the screen, you are only allowed to create one stream, and you have unlimited time to postion your blocks and ponder your one move.
I thought the soundtrack for the game was well done. It is a mix of both cheery and soothing piano tunes.
If there is one criticism it's that the single-player storyline seems to be geared towards young children, but the difficulty level of the puzzles is geared towards adults. But it's not good to be too critical on that point, I'm astounded the game had a storyline at all!
If you like Tetris-style games or really any puzzle games at all you should check out Tidalis.