Answer:
dependent-samples t test
Explanation:
Here we want to test the effect of game Dance Dance Revolution (DDR) on heart rate. 
 
The hypothesis is 
 

 
where, 
 

 
Where Xi = heart rate before playing the game Dance Dance Revolution (DDR) 
 
Yi = heart rate after playing the game Dance Dance Revolution (DDR) 
 
This test is paired t-test( dependent sample t test). 
 
To measure the effect of experiment. (before - after condition)