Games like Unending
Games like Unending include Into the Breach, FTL: Faster Than Light, Slay the Spire 2, Peglin, and LYNE. We matched them by the tags players give Unending on Steam (Puzzle, Strategy, Roguelite, Grid-Based Movement, and Turn-Based Combat): closest matches first, and among equally close ones the better-known games.

Into the Breach
Shared: Strategy · Puzzle · Roguelite

FTL: Faster Than Light
Shared: Strategy · Perma Death · Roguelike

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

Peglin
Shared: Roguelite · Strategy · Perma Death

LYNE
Shared: Puzzle · Logic · Procedural Generation

Crown Trick
Shared: Turn-Based Combat · Roguelite · Strategy

Darkest Dungeon®
Shared: Turn-Based Combat · Strategy · Perma Death

Sol Cesto
Shared: Puzzle · Strategy · Procedural Generation

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

Patrick's Parabox
Shared: Puzzle · Logic · Abstract

Hades
Shared: Roguelite · Hack and Slash · Indie

Darkest Dungeon® II
Shared: Roguelite · Turn-Based Combat · Perma Death

Hexcells
Shared: Puzzle · Strategy · Logic

Loop Hero
Shared: Roguelite · Tactical · Strategy

Inscryption
Shared: Puzzle · Roguelite · Strategy

Mini Metro
Shared: Puzzle · Strategy · Minimalist

Baba Is You
Shared: Puzzle · Logic · Indie

Crying Suns
Shared: Strategy · Roguelite · Indie

14 Minesweeper Variants
Shared: Puzzle · Strategy · Logic

Hexcells Infinite
Shared: Puzzle · Strategy · Logic

Othercide
Shared: Strategy · Turn-Based Combat · Roguelite

9 Kings
Shared: Strategy · Roguelite · Turn-Based Combat

Void War
Shared: Roguelite · Strategy · Perma Death

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