A Gentle Rain is a solitaire (and possibly co-op) tile laying game about water lilies blooming in a pond. This is a very small box game designed by Kevin Wilson (designer of Arkham Horror, among others), and available to purchase from Mondo Games' website.
All you have to do in A Gentle Rain is match up flower halves by placing tiles in the best possible way. You start the game with a stack of tiles and place one down each turn. The tile you place must match with at least one other already placed flower. Your goal is to complete four different flowers by perfectly matching four tiles. If you do so, you place one wooden flower token in the hole in the middle of the tiles. You keep playing in this manner until either you place all the wooden tokens and win, or run out of tiles and lose. If you win, you may count how many tiles are left in the stack and try to beat your score next time.