Games like Flatland Vol.2
Games like Flatland Vol.2 include Celeste, Geometry Dash, Super Meat Boy, LIMBO, and Thomas Was Alone. We matched them by the tags players give Flatland Vol.2 on Steam (Precision Platformer, Side Scroller, Puzzle Platformer, Stealth, and Arcade): closest matches first, and among equally close ones the better-known games.

Celeste
Shared: Precision Platformer · Difficult · 2D Platformer

Geometry Dash
Shared: Precision Platformer · Difficult · 2D

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

LIMBO
Shared: Puzzle Platformer · 2D · Atmospheric

Thomas Was Alone
Shared: Side Scroller · Precision Platformer · Puzzle Platformer

SANABI
Shared: 2D Platformer · Action · 2D

Downwell
Shared: Precision Platformer · Arcade · 2D Platformer

Jump King
Shared: Precision Platformer · Difficult · 2D

Mark of the Ninja
Shared: Stealth · Side Scroller · 2D

VVVVVV
Shared: Precision Platformer · 2D Platformer · Difficult

N++ (NPLUSPLUS)
Shared: Precision Platformer · 2D Platformer · Difficult

Rogue Legacy 2
Shared: Arcade · Action · Difficult

Mark of the Ninja: Remastered
Shared: Stealth · Side Scroller · 2D

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

Braid
Shared: Puzzle Platformer · 2D Platformer · 2D

Exit the Gungeon
Shared: Arcade · Action · 2D

DEADBOLT
Shared: Stealth · Side Scroller · 2D

Super Meat Boy Forever
Shared: Precision Platformer · Difficult · Action

oO
Shared: Precision Platformer · Arcade · Difficult

Prince of Persia The Lost Crown
Shared: Side Scroller · Precision Platformer · 2D Platformer

Will You Snail?
Shared: Precision Platformer · Difficult · Puzzle Platformer

Hollow Knight
Shared: Difficult · 2D · Atmospheric

A Dance of Fire and Ice
Shared: Difficult · Arcade · 2D

Super Hexagon
Shared: Difficult · Arcade · Indie