Games like Riichi Mahjong
Games like Riichi Mahjong include Wingspan, Armello, Gremlins, Inc., Root, and The Conquest of Go. We matched them by the tags players give Riichi Mahjong on Steam (Mahjong, Strategy, Education, Tutorial, and Casual): closest matches first, and among equally close ones the better-known games.

Wingspan
Shared: Strategy · Board Game · Casual

Armello
Shared: PvP · Strategy · Turn-Based Strategy

Gremlins, Inc.
Shared: Strategy · Tabletop · Board Game

Root
Shared: Strategy · Tabletop · Board Game

The Conquest of Go
Shared: Strategy · Tabletop · Education

Liars Bar
Shared: PvP · Casual · Tabletop

Sid Meier’s Civilization® VI
Shared: Strategy · Turn-Based Strategy · PvP

Plague Inc: Evolved
Shared: Strategy · Casual · PvP

UNO
Shared: Strategy · Casual · Tabletop

Rento Fortune: Online Dice Board Game (大富翁)
Shared: Strategy · Casual · Board Game

Richman10
Shared: Strategy · Casual · Tabletop

Carcassonne - Tiles and Tactics
Shared: Strategy · Casual · Board Game

Dorfromantik
Shared: Strategy · Casual · Turn-Based Strategy

Chess Ultra
Shared: Strategy · Tabletop · Board Game

ShellShock Live
Shared: Strategy · Casual · 2D

Talisman: Digital Classic Edition
Shared: Strategy · Tabletop · Board Game

Richman 11
Shared: Casual · Strategy · PvP

Your Only Move Is HUSTLE
Shared: Strategy · Turn-Based Strategy · 2D

Just Go
Shared: Strategy · Casual · Turn-Based Strategy

100% Orange Juice
Shared: Strategy · Board Game · Casual

Gaia Project
Shared: Strategy · Casual · PvP

Through the Ages
Shared: Strategy · Tabletop · Board Game

Hasbro's BATTLESHIP
Shared: Strategy · Board Game · Casual

Bloons TD 6
Shared: Strategy · Casual · Singleplayer