Game description from the publisher:
KerFlip! is a fast-thinking word game that rewards you for making anagrams from a group of letter tiles faster than your opponents can. At the beginning of each round, players simultaneously drop a number of tiles onto the board, flip them all ivory side up, then race to find a word in the tiles and call it out. After everyone's called out a word, players score their word in the call-out order.
The first player arranges the tiles she needs to form her word. All the tiles are ivory, so she scores 10 points per tile. Then she flips all of the tiles in her word over to their orange side. Here's where it gets tricky. The second player now arranges the tiles to form his word. The ivory tiles in his word are still worth 10 points each, but the orange tiles he uses are only worth 5 points, now. He scores his word then flips any ivory tiles he used to their orange side. Once a tile is orange, it stays orange, so as each player scores their word the number of orange tiles grows. Calling out your word faster than anyone else is very advantageous!
Some tiles, identified by a small number in the bottom right corner, are "premium tiles"; they're a little harder to use so you get to draw bonus point cards if you do use those tiles. Don't peek at your cards, they're a secret until the end of the game.
After each round, players tally up their scores and push the orange tiles out of the game. Ivory tiles go back to the draw bag for the next round.