Step 1

Combine lime gelatin and 1-1/2 cups boiling water; stir until gelatin is dissolved. Pour into a lightly greased 8x4-in. loaf pan; chill until very firm. Repeat to make the strawberry and orange gelatins in separate pans. Combine the crumbs, sugar and butter; press into a greased 13x9-in. dish. Chill.

Step 2

Meanwhile, in a small bowl, soften unflavored gelatin in cold water for 5 minutes. In a small saucepan, bring pineapple juice to a boil. Stir in unflavored gelatin until dissolved. Transfer to a large bowl; set aside until room temperature, 20-30 minutes.

Step 3

When flavored gelatins are firm, cut into 1/2-in. cubes. In a large bowl, whisk whipped topping into pineapple juice mixture. Gently fold 2/3 of the cubes into whipped topping mixture. Spoon over crust; top with the remaining cubes. Chill for at least 2 hours.