<P> A defensive strategy would advise playing a high card in order to reduce the point value of the hand . However, an offensive strategy would suggest playing a 0 when the player wants to continue on the current color, because it is less likely to be matched by another 0 of a different color (there is only one 0 of each color, but two of each 1--9). </P> <P> A player holding only one card is required to call out "Uno" or risk being penalized if caught . A player who calls "Uno" risks being the target of concerted action by the other players, who may be able to use action cards to prevent that player from going out . Depending on the level and seriousness of play, some players may deliberately avoid saying "Uno", in the hope of avoiding detection and then going out on the next turn . For this reason, it is useful to conceal how many cards are in your hand, and to keep track of how many cards every other player holds . </P> <P> Little has been published on the optimal strategy for the game of Uno . Simulations of games may shed some light on the matter . Attempts to reduce point count in a player's hands can be "read" by other players if too transparent . This information can be exploited by other players, and it follows that a mixed strategy may be more appropriate . </P> <P> Some work has been done into the psychology of Uno as it relates to individual and group behavior . Players may exhibit physical tells, in which a subtle, often repeated, cue inadvertently reveals their state of mind during a game . Alternatively, they may change their playing style, switching from an aggressive card - shedding strategy to a more subdued one, or vice versa . </P>

In uno can you end on a power card