Games like Ragnar
Games like Ragnar include Huntdown, SANABI, Broforce, Alex Jones: NWO Wars, and Kero Blaster. We matched them by the tags players give Ragnar on Steam (Hero Shooter, Side Scroller, 2D Platformer, Shoot 'Em Up, and Platformer): closest matches first, and among equally close ones the better-known games.

Huntdown
Shared: Side Scroller · Shooter · Shoot 'Em Up

SANABI
Shared: 2D Platformer · Action · Pixel Graphics

Broforce
Shared: Platformer · Side Scroller · 2D

Alex Jones: NWO Wars
Shared: 2D Platformer · Side Scroller · Shoot 'Em Up

Kero Blaster
Shared: Side Scroller · Shoot 'Em Up · Platformer

Contra: Operation Galuga
Shared: 2D Platformer · Platformer · Shooter

Anomaly Agent
Shared: Side Scroller · 2D Platformer · Platformer

METAL SLUG
Shared: Side Scroller · Arcade · Shoot 'Em Up

Terminator 2D: NO FATE
Shared: Side Scroller · 2D Platformer · Arcade

Gravity Circuit
Shared: Platformer · 2D Platformer · Action

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

METAL SLUG 3
Shared: Side Scroller · Arcade · Shooter

Blazing Chrome
Shared: Side Scroller · Shoot 'Em Up · Action

Guns of Fury
Shared: Platformer · Shoot 'Em Up · Shooter

Warhammer 40,000: Shootas, Blood & Teef
Shared: Side Scroller · 2D Platformer · Shoot 'Em Up

Momodora: Reverie Under The Moonlight
Shared: Side Scroller · 2D Platformer · 2D

Guns, Gore & Cannoli
Shared: Side Scroller · Shoot 'Em Up · 2D

Shovel Knight: Treasure Trove
Shared: Platformer · Side Scroller · 2D

Rogue Legacy 2
Shared: Platformer · Arcade · Action

Contra Anniversary Collection
Shared: Side Scroller · Platformer · Shooter

Downwell
Shared: Platformer · 2D Platformer · Arcade

Katana ZERO
Shared: Platformer · 2D Platformer · Action

Skul: The Hero Slayer
Shared: Platformer · Action · 2D

Celeste
Shared: 2D Platformer · Platformer · Pixel Graphics