Primrose is a deep game, it's an homage to Go, Othello, the best of the Match-3s, and maybe to the burgeoning trend of threading user content creation into gameplay with seamless poise. Like most of Rohrer's work, you start out a bit unclear as to what to do, but through experimentation you stumble upon that moment of enlightenment where both the rules and the system's depth become clear. This time, Jason has traded his ambition of redefining our vista of the human condition for the ambition of making a system so deep that autistic savants will fecklessly try to sprint up the leader boards. It turns out to be a profitable trade.
The game involves surrounding blocks of one color with blocks of another color, and you can use corners and edges to corral this racial segregation. When surrounded, the central blocks disappear for points and the oppressor blocks are changed to the color of their former victims. Finally, you place blocks in pairs, the first block you can place in any free square, the second must be placed in the same row or column, so your moves are constrained.
Those three rules are it, and yet the geometric scoring scale that emerges from this (including chain reactions) makes it easy for a new player to score a few dozen points, and for a sick genius to score in the billions. The result is a sense of creating your own puzzle levels, each move you make sets up the terrain of your future moves. It's like Little Big Planet as a puzzle game, the design and play integrated even more seamlessly, so that you cannot play without designing. The flip-side to that is the transformation mechanic always introduces chaos. It's easy to set up chambers to clear massive swaths of blocks, but it's hard to predict three steps ahead how the transformations will warp your petty, rigid geometries into snake-like warps. Ultimately you end up filling the screen and running out of options, though clever players can clear the screen and keep going for what seems like a Valhalla of puzzle-dom.
The game does have a sort of pre-designed progression structure in that after so many moves, new blocks are introduced. Then after all seven types of blocks are introduced, the game starts throwing sets of a single block type, like thirty of them, that you must deploy without blocking yourself in. There's a leaderboard but in this version, no multiplayer. Let me know if you think this deserves a DSi port with turn-based multiplayer and the ability to read your opponent's face, because if enough people are into it, I can make it happen.