Games like Sketchy Marathon
Games like Sketchy Marathon include Rogue Legacy 2, SHINOBI: Art of Vengeance, pureya, Hollow Knight, and SANABI. We matched them by the tags players give Sketchy Marathon on Steam (Action, Casual, Platformer, Runner, and Arcade): closest matches first, and among equally close ones the better-known games.

Rogue Legacy 2
Shared: Action · Platformer · Arcade

SHINOBI: Art of Vengeance
Shared: Action · Platformer · 2D Platformer

pureya
Shared: Casual · Arcade · Action

Hollow Knight
Shared: Platformer · 2D · Singleplayer

SANABI
Shared: Action · 2D Platformer · Platformer

Rogue Legacy
Shared: Platformer · Action · Singleplayer

Ninja Kiwi Archive
Shared: Casual · Action · Arcade

Broforce
Shared: Action · Platformer · 2D

Super Fancy Pants Adventure
Shared: Action · Platformer · Casual

Skul: The Hero Slayer
Shared: Action · Platformer · Indie

Oozi: Earth Adventure
Shared: Platformer · Casual · Action

8BitBoy™
Shared: Action · Platformer · Casual

Katana ZERO
Shared: Action · Platformer · 2D Platformer

Downwell
Shared: Platformer · Action · Arcade

BIT.TRIP RUNNER
Shared: Platformer · Action · Runner

Dino Run DX
Shared: Action · Arcade · Runner

Vector
Shared: Action · Platformer · Runner

Timberman
Shared: Casual · Action · Arcade

Sonic Origins
Shared: Action · Platformer · Casual

Gravity Circuit
Shared: Action · Platformer · 2D Platformer

Mark of the Ninja
Shared: Platformer · Action · Side Scroller

Twin Shot Deluxe
Shared: Action · Casual · Arcade

Shovel Knight: Treasure Trove
Shared: Platformer · Action · 2D

Geometry Dash
Shared: Platformer · 2D · Singleplayer