Games like NGU IDLE
Games like NGU IDLE include Banana, Idle Champions of the Forgotten Realms, IdleOn - The Incremental MMO, Bongo Cat, and Cookie Clicker. We matched them by the tags players give NGU IDLE on Steam (Free to Play, Incremental, Idler, Indie, and Adventure): closest matches first, and among equally close ones the better-known games.

Banana
Shared: Free to Play · Incremental · Idler

Idle Champions of the Forgotten Realms
Shared: Free to Play · Idler · Incremental

IdleOn - The Incremental MMO
Shared: Free to Play · Idler · Incremental

Bongo Cat
Shared: Free to Play · Idler · Incremental

Cookie Clicker
Shared: Incremental · Idler · Indie

Cell to Singularity - Evolution Never Ends
Shared: Free to Play · Incremental · Idler

TBH: Task Bar Hero
Shared: Free to Play · Idler · Indie

Where Winds Meet
Shared: Free to Play · Singleplayer · Adventure

Melvor Idle
Shared: Idler · Indie · Adventure

Dragon Cliff
Shared: Idler · Incremental · RPG

There Is No Game: Wrong Dimension
Shared: Indie · Adventure · Funny

To the Moon
Shared: Indie · Adventure · Singleplayer

SuchArt: Creative Space
Shared: Free to Play · Simulation · Singleplayer

The Sims™ 4
Shared: Free to Play · Simulation · Singleplayer

Your Chronicle
Shared: Idler · Incremental · Free to Play

Sultan's Game
Shared: Singleplayer · Adventure · RPG

Outcore: Desktop Adventure
Shared: Free to Play · Adventure · Psychological Horror

Crush Crush
Shared: Free to Play · Incremental · Singleplayer

Chinese Parents
Shared: Indie · Simulation · Psychological Horror

Samsara Room
Shared: Free to Play · Indie · Adventure

Transformice
Shared: Free to Play · Funny · Adventure

Dr. Langeskov, The Tiger, and The Terribly Cursed Emerald: A Whirlwind Heist
Shared: Free to Play · Indie · Funny

鬼谷八荒 Tale of Immortal
Shared: Simulation · Singleplayer · RPG

Swag and Sorcery
Shared: Incremental · Indie · RPG