Games like Lumpy
Games like Lumpy include Librarian: Tidy Up the Arcane Library!, Placid Plastic Duck Simulator, Keep on Mining!, ISLANDERS, and Mini Motorways. We matched them by the tags players give Lumpy on Steam (Casual, Relaxing, Collectathon, Idler, and Building): closest matches first, and among equally close ones the better-known games.

Librarian: Tidy Up the Arcane Library!
Shared: Relaxing · Collectathon · Casual

Placid Plastic Duck Simulator
Shared: Relaxing · Collectathon · Casual

Keep on Mining!
Shared: Casual · Relaxing · Idler

ISLANDERS
Shared: Relaxing · Building · Puzzle

Mini Motorways
Shared: Casual · Relaxing · Puzzle

LYNE
Shared: Relaxing · Casual · Puzzle

Townscaper
Shared: Relaxing · Casual · Building

Hook
Shared: Casual · Relaxing · Puzzle

Keep on Mining! - Worlds
Shared: Casual · Relaxing · Idler

Zup! S
Shared: Casual · Relaxing · Puzzle

Coin Pusher Casino
Shared: Casual · Relaxing · Arcade

My Dream Setup
Shared: Relaxing · Building · Casual

Cookie Clicker
Shared: Casual · Idler · Collectathon

Chill with You : Lo-Fi Story
Shared: Casual · Relaxing · Idler

Dorfromantik
Shared: Relaxing · Casual · Puzzle

klocki
Shared: Relaxing · Casual · Puzzle

Supermarket Chaos
Shared: Relaxing · Collectathon · Casual

Nodebuster
Shared: Casual · Idler · Arcade

Ropuka's Idle Island
Shared: Relaxing · Idler · Casual

A Game About Feeding A Black Hole
Shared: Casual · Relaxing · Idler

Tiny Glade
Shared: Relaxing · Building · Casual

Sizeable
Shared: Casual · Relaxing · Puzzle

Shelldiver
Shared: Casual · Relaxing · Idler

Hexcells Infinite
Shared: Casual · Relaxing · Puzzle