The old 3M line included some old classics such as chess, go and backgammon and some updated versions of classic games such as Oh-Wah-Ree (mancala) and Breakthru (tablut) but much of the line were original designs such as Acquire and Stocks & Bonds. Among the latter was ploy, an abstract strategy game that affected a modernistic look and style of play.
In ploy the moves of the pieces are indicated by the shape of the plastic pieces themselves. Each piece has one or more ridges which graphically depict not only the direction the piece can go but how many points. The lances, for example, can move three points because they have three ridges, and have a choice of three directions. The shields, which have just one ridge, can move just one space in one direction.
The game board is a 9x9 criss-cross grid of points that are connected by horizontal, vertical and diagonal lines, resulting in 8 potential directions of movement. The object of the game is to capture the enemy's "commander," who can move just a single point (in an exception to the usual movement scheme), but has the most options of any other pieces with four possible move directions.
The cleverness of the design is that pieces come in several varieties. While every lance can move three points, they also come in three different varieties as far as directions.
Each army deploys in three rows, with the fastest and most flexible pieces closest to the player. The back row comprises the commander flanked to either side by a total of six lances in three different varieties. The second row has five "probes" (move 2 spaces) also in three varieties and the front row has three shields (one-space move).
During a player's turn he can conduct either a "motion" move which allows a piece to move up to the number points shown by its ridges in a direction indicated by the ridges or a "direction" move, which allows a piece to rotate so it's ridges line up in new directions. A shield, only, is allowed to make a motion move followed by a direction move. (So a shield can move in the direction it started facing, but then change its facing, but it cannot change facing and then move.
Compared to chess and similar abstracts Ploy features a more wide-open style of play. There's one fewer piece on each side maneuvering on a board with 17 more spaces and double the potential move directions. Unlike chess, no pieces can sweep from one end of the board to the other. The signature feature of Ploy is that no piece can really defend itself. The most mobile pieces are still helpless in 5 out of 8 directions.
Ploy is a little easier to teach than many similar abstracts because the moves are right on the pieces, so it's a good choice for younger players. Being far less popular and analyzed than chess, it provides a more level playing field for beginners while still being a good introduction to the kind of strategic and tactical thinking needed for chess.
It's never been reissued since 3M days but it's not hard to find on eBay in good condition, so it's still a good choice to seek out.
The game includes 4-player and partnership options with a slightly different setup and mix of pieces, but otherwise the same rules.