Add 3/4-cup boiling water to blue gelatin mix; stir 2 min. until completely dissolved. Add 1/2-cup ice cubes; stir until melted. Pour into crust; refrigerate 5 to 10 min. or until set but not firm.
Repeat to dissolve red gelatin mix in separate bowl; stir in remaining ice cubes. Cool 5 min. or until slightly thickened.
Spread whipped topping over blue gelatin layer; cover with red gelatin. Refrigerate 2 hours or until firm.