Games like Rikki & Vikki
Games like Rikki & Vikki include Broforce, Cuphead, Shovel Knight: Treasure Trove, PICO PARK, and Portal 2. We matched them by the tags players give Rikki & Vikki on Steam (Arcade, Puzzle Platformer, Difficult, Pixel Graphics, and 2D): closest matches first, and among equally close ones the better-known games.

Broforce
Shared: Co-op · Pixel Graphics · 2D

Cuphead
Shared: Difficult · Co-op · Platformer

Shovel Knight: Treasure Trove
Shared: Pixel Graphics · Platformer · 2D

PICO PARK
Shared: Co-op · Puzzle Platformer · Local Co-Op

Portal 2
Shared: Puzzle Platformer · Puzzle · Platformer

Celeste
Shared: Difficult · Pixel Graphics · Platformer

UFO 50
Shared: Pixel Graphics · Arcade · 2D

LIMBO
Shared: Puzzle Platformer · Puzzle · Platformer

Human Fall Flat
Shared: Co-op · Puzzle · Puzzle Platformer

Out There Somewhere
Shared: Pixel Graphics · Platformer · Puzzle

Defy Gravity Extended
Shared: Puzzle Platformer · Platformer · Puzzle

BADLAND: Game of the Year Edition
Shared: 2D · Co-op · Action

It Takes Two
Shared: Co-op · Puzzle · Puzzle Platformer

Spelunky
Shared: Difficult · Platformer · 2D

ibb & obb
Shared: Co-op · Puzzle · Puzzle Platformer

SUPER CHICKEN JUMPER
Shared: Arcade · Difficult · 2D

ANIMAL WELL
Shared: Puzzle Platformer · Pixel Graphics · Puzzle

Hollow Knight
Shared: Difficult · Platformer · 2D

Rogue Legacy 2
Shared: Arcade · Platformer · Difficult

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

Lara Croft and the Guardian of Light
Shared: Co-op · Action · Puzzle Platformer

Squishy the Suicidal Pig
Shared: Puzzle Platformer · Puzzle · Platformer

Enter the Gungeon
Shared: Difficult · Pixel Graphics · Co-op

SANABI
Shared: Pixel Graphics · Action · 2D