While Triple Deluxe and Return to Dreamland mastered and polished the Kirby formula, both felt a little uncreative. They were extremely fun and cute, but they lacked a certain element necessary in differentiating them from rest of the series. That element being an awesome, all powerful Kirby mech. Fortunately, Kirby:
The Ratchet and Clank series is known for its creative weapons, creative characters, creative locations, and just being all around creative. The first game in the series set an unbreakable precedent. The next buffed out much of the stains present in the first while throwing in a lot of new mechanics.