24 games ranked by how much the tags Steam players vote on them overlap with Ultimate Sudoku Collection's. A rare tag counts for far more than one that sits on half the store, and popularity never moves a game up.
What they share most: Free to Play, Casual, Difficult, Puzzle, Board Game.

1·Impossible Runner
97% match · Free to Play, Casual
64% of 237 reviews positive

2·Sigils of Elohim
95% match · Free to Play, Puzzle
91% of 1,203 reviews positive

3·Onirim - Solitaire Card Game
93% match · Free to Play, Board Game
86% of 273 reviews positive

4·Pixel Puzzles Traditional Jigsaw Puzzles
92% match · Free to Play, Board Game
76% of 572 reviews positive

5·Krosmaster Arena
91% match · Free to Play, Board Game
62% of 298 reviews positive

6·The Dummy Experiment
90% match · Free to Play, Difficult
66% of 244 reviews positive

7·You Have 10 Seconds 2
90% match · Free to Play, Casual
91% of 669 reviews positive

8·Fork Parker's Holiday Profit Hike
89% match · Free to Play, Difficult
84% of 725 reviews positive

9·Worm.is: The Game
88% match · Free to Play, Casual
81% of 4,725 reviews positive

10·App 1236390
88% match · Free to Play, Casual
73% of 332 reviews positive

11·Business Tour - Board Game with Online Multiplayer(大富翁)
88% match · Board Game, Free to Play
60% of 80,528 reviews positive · 212 playing

12·Fox & Flock
87% match · Board Game, Casual
85% of 201 reviews positive

13·Ludo Supremo
87% match · Board Game, Casual
55% of 147 reviews positive

14·Lost Lands: Mahjong
86% match · Free to Play, Casual
91% of 5,483 reviews positive

15·Overclocked
86% match · Free to Play, Difficult
93% of 320 reviews positive

16·Drop Alive
85% match · Free to Play, Casual
89% of 1,573 reviews positive

17·Catan Universe
84% match · Board Game, Free to Play
47% of 18,222 reviews positive

18·Core Defense: Prelude
84% match · Free to Play, Casual
87% of 212 reviews positive

19·The Lord of the Rings: Journeys in Middle-earth
84% match · Board Game, Free to Play
91% of 938 reviews positive

20·Dots eXtreme
83% match · Board Game, Casual
86% of 116 reviews positive

21·Mini-Dead
83% match · Free to Play, Difficult
94% of 925 reviews positive

22·Swarm
83% match · Free to Play, Difficult
93% of 283 reviews positive

23·RISK: Global Domination
83% match · Board Game, Free to Play
79% of 41,730 reviews positive · 1,415 playing

24·Mission Zigloton
83% match · Free to Play, Difficult
94% of 251 reviews positive
The closest matches to Ultimate Sudoku Collection on Steam are Impossible Runner, Sigils of Elohim, Onirim - Solitaire Card Game, Pixel Puzzles Traditional Jigsaw Puzzles, Krosmaster Arena. They rank highest because their Steam community tags overlap most with Ultimate Sudoku Collection's, and shared tags include Free to Play, Casual, Difficult.
Every game is described by the tags Steam players vote on it. Rare, specific tags such as Free to Play, Casual, Difficult count far more than catch-all ones like "Indie" or "Singleplayer", and each game is scored on how closely its whole tag profile matches Ultimate Sudoku Collection's. Popularity never affects the ranking.