Games like Radii
Games like Radii include Celeste, SANABI, Super Meat Boy, VVVVVV, and The End Is Nigh. We matched them by the tags players give Radii on Steam (Action, Adventure, Platformer, 2D Platformer, and Precision Platformer): closest matches first, and among equally close ones the better-known games.

Celeste
Shared: Precision Platformer · Platformer · Pixel Graphics

SANABI
Shared: Action · Adventure · Pixel Graphics

Super Meat Boy
Shared: Platformer · Precision Platformer · 2D Platformer

VVVVVV
Shared: Platformer · Precision Platformer · Pixel Graphics

The End Is Nigh
Shared: Platformer · Precision Platformer · Adventure

Katana ZERO
Shared: Action · Platformer · Pixel Graphics

Downwell
Shared: Precision Platformer · Platformer · Pixel Graphics

Jump King
Shared: Precision Platformer · Adventure · Platformer

Skul: The Hero Slayer
Shared: Action · Pixel Graphics · 2D

Rain World
Shared: Platformer · Pixel Graphics · 2D

Pizza Tower
Shared: 2D Platformer · Platformer · Action

BlazBlue Entropy Effect
Shared: Action · Platformer · 2D

Dungeon Munchies
Shared: Action · Adventure · Pixel Graphics

Shovel Knight: Treasure Trove
Shared: Platformer · Adventure · Pixel Graphics

Broforce
Shared: Action · Platformer · Pixel Graphics

Hollow Knight
Shared: Platformer · 2D · Adventure

Sonic Origins
Shared: Action · Adventure · 2D Platformer

Dead Cells
Shared: Adventure · 2D · Pixel Graphics

Dust: An Elysian Tail
Shared: Action · Platformer · Adventure

Rusted Moss
Shared: Platformer · Action · Adventure

Gravity Circuit
Shared: Action · Platformer · 2D

Terraria
Shared: Adventure · 2D · Pixel Graphics

Deadlight
Shared: Action · Platformer · Adventure

Smilemo
Shared: Action · Adventure · Platformer