Percepts was the free Odyssey game you got for registering your Odyssey.
In this game, you must determine where to go on the screen and get there before your opponent does. It uses cards. Percepts comes with two decks (Purple and Green) of 15 cards each, a screen overlay and a set of instructions. There are two games described in the instructions, Patterns and Symbols.
Patterns: In this game, the 15 green cards are layed out, face-up in a 3x5 grid, just like the blank rectangles on the overlay. Then a player draws a Purple card from unused Purple deck.
You must then study the pattern (the 3x3 grid) on the card and find the matching green card. Then it's a race, using the controllers to maneuver the player spots to the corresponding position on the overlay! The first to get there win a green card! When there are no more green cards, the one with the most green cards wins.
Symbols: Symbols is basically the same game, but after studying the green cards, they must all be turned over. And this time simpler symbols are to be remembered not dot patterns.