Games like Eternal Ninja
Games like Eternal Ninja include Brawlhalla, Planet of Lana, Trine 2: Complete Story, SANABI, and Trine Enchanted Edition. We matched them by the tags players give Eternal Ninja on Steam (Free to Play, Puzzle Platformer, Action, Adventure, and 2D Platformer): closest matches first, and among equally close ones the better-known games.

Brawlhalla
Shared: Free to Play · 2D Platformer · Casual

Planet of Lana
Shared: Puzzle Platformer · Action · 2D Platformer

Trine 2: Complete Story
Shared: Puzzle Platformer · 2D Platformer · Action-Adventure

SANABI
Shared: Action · 2D Platformer · Adventure

Trine Enchanted Edition
Shared: Puzzle Platformer · 2D Platformer · Action-Adventure

Portal 2
Shared: Puzzle Platformer · Puzzle · Platformer

Webbed
Shared: 2D Platformer · Puzzle Platformer · Physics

LIMBO
Shared: Puzzle Platformer · Adventure · Puzzle

Human Fall Flat
Shared: Adventure · Puzzle Platformer · Action

Celeste
Shared: 2D Platformer · Precision Platformer · Adventure

Chained Together
Shared: Adventure · Puzzle Platformer · Casual

Trine 5: A Clockwork Conspiracy
Shared: Action · Adventure · Puzzle Platformer

Janosik
Shared: Action · Adventure · Free to Play

BEEP
Shared: Adventure · Action · Platformer

Defy Gravity Extended
Shared: Puzzle Platformer · Action · Platformer

Sonic Superstars
Shared: Action · Adventure · 2D Platformer

The Darkest Tales — Into the Nightmare
Shared: Free to Play · Adventure · 2D Platformer

Where Winds Meet
Shared: Free to Play · Adventure · Action-Adventure

Braid
Shared: Puzzle Platformer · 2D Platformer · Puzzle

Pikuniku
Shared: Adventure · Casual · Action

I wanna be the Creator
Shared: Action · Adventure · Action-Adventure

FEZ
Shared: Adventure · Puzzle Platformer · Puzzle

Laughing to Die
Shared: Adventure · Casual · 2D Platformer

Sonic Origins
Shared: Action · Adventure · 2D Platformer