Which Kirby game introduced 3D graphics to the series while keeping side-scrolling gameplay?

Kirby 64: The Crystal Shards introduced 3D graphics to the Kirby series while retaining side-scrolling gameplay.

Released for the Nintendo 64 in 2000, Kirby 64 presents characters and environments with 3D computer graphics but keeps movement largely on a two-dimensional path. This 2.5D design let HAL Laboratory modernize Kirby's look without abandoning the straightforward platforming style established by earlier games.

The story follows Kirby and Ribbon as they recover a sacred crystal shattered by Dark Matter. Across six planets, players search for crystal shards and confront corrupted allies and enemies. The game also introduced Power Combos, allowing Kirby to combine two copy abilities into new powers, such as fire-based and electric variations.

A common mix-up is calling Kirby 64 a fully 3D platformer. Its models and scenery are three-dimensional, but the gameplay remains side-scrolling, with the Nintendo 64's D-pad used for movement. Kirby Air Ride is also associated with 3D visuals, yet it is a racing spin-off rather than the series' first game to use 3D graphics. Kirby 64 additionally includes three four-player mini-games.