Games like Assassin's Belief
Games like Assassin's Belief include Reus, XCOM 2, Slay the Spire 2, Plants vs. Zombies GOTY Edition, and Bloons TD 6. We matched them by the tags players give Assassin's Belief on Steam (Strategy, Racing, God Game, 2D Platformer, and 2D): closest matches first, and among equally close ones the better-known games.

Reus
Shared: Strategy · God Game · Singleplayer

XCOM 2
Shared: Strategy · Turn-Based Combat · Singleplayer

Slay the Spire 2
Shared: Strategy · Turn-Based Combat · 2D

Plants vs. Zombies GOTY Edition
Shared: Strategy · Singleplayer · 2D

Bloons TD 6
Shared: Strategy · Singleplayer · 2D

The Last Spell
Shared: Strategy · Singleplayer · Turn-Based Combat

Pit People®
Shared: Strategy · Turn-Based Combat · 2D

Darkest Dungeon®
Shared: Turn-Based Combat · Strategy · Singleplayer

Kingdom Rush - Tower Defense
Shared: Strategy · 2D · Singleplayer

Library Of Ruina
Shared: Strategy · Turn-Based Combat · Singleplayer

Stoneshard
Shared: Strategy · 2D · Singleplayer

Kingdom Rush 5: Alliance TD
Shared: Strategy · 2D · Singleplayer

ShellShock Live
Shared: Strategy · 2D · Early Access

Motorsport Manager
Shared: Racing · Strategy · Singleplayer

Kingdom Rush Frontiers - Tower Defense
Shared: Strategy · 2D · Singleplayer

The Escapists
Shared: Strategy · 2D · Singleplayer

Kingdom Rush Vengeance - Tower Defense
Shared: Strategy · 2D · Singleplayer

Plague Inc: Evolved
Shared: Strategy · Singleplayer · 2D

觅长生
Shared: Strategy · Turn-Based Combat · Singleplayer

Kingdom Rush Origins - Tower Defense
Shared: Strategy · 2D · Singleplayer

Warhammer 40,000: Mechanicus
Shared: Strategy · Turn-Based Combat · Singleplayer

Game Dev Tycoon
Shared: Strategy · Singleplayer · 2D

Doodle Empires
Shared: Strategy · God Game · 2D

The World of Kungfu: Dragon and Eagle
Shared: Strategy · Turn-Based Combat · 2D