40 children with cancer who fulfills the inclusion criteria will be included. Participants will be recruited from King Fahad Children's Cancer Center, King Fahad Medical City and King Khaled University Hospital. After obtaining written formal consent, children will be randomly assigned to two groups, control and experimental. Experimental group will play 60 minutes of Wii physical activity games for three weeks, twice each week. while control group will receive conventional therapy. Fatigue will be assessed using pediatric multidimensional fatigue scale- child proxy before, weekly during the study and after. Functional capacity will be measured by six minute walk test before and after study duration, and physical activity will be repeatedly measured by godin-shephard leisure time physical activity questionnaire. All data will be analyzed using appropriate statistical analysis.

The intervention group:

The investigator will:

• handle accompanying each child to the play room, turn on the Wii and ask the child to choose the game he/she prefers to play from the games provided by wii console that requires the movement of the whole body: upper, lower and trunk.
• Monitor the child while playing, helping with the instructions of the game if the child needs assistance as it is only provided in English from the console.
• heart rate and oxygen saturation are planned to be measured every 15 minutes.

The duration is designed to be 60 minutes per session, but the child is allowed to rest for the time needed during the session if he/she feels tired. or if the oxygen saturation of the child reaches 93. or the heart rate reaches the predicted maximum heart rate.

Inclusion Criteria:

• diagnosed with leukemia, receiving chemotherapy, or off therapy within 6 months.

Exclusion Criteria:

• bone / pulmonary metastasis, having physical or cognitive disability preventing the child from being able to use the controller and board of the console.