24 games ranked by how much the tags Steam players vote on them overlap with Jagged Alliance 1: Gold Edition'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: Turn-Based Tactics, Turn-Based, Tactical RPG, Tactical, Classic, Strategy.

1·Silent Storm Gold Edition
92% match · Turn-Based Tactics, Turn-Based
88% of 1,073 reviews positive

2·Deadlock II: Shrine Wars
91% match · Classic, Strategy
71% of 82 reviews positive

3·Etherlords
91% match · Turn-Based, Turn-Based Strategy
43% of 237 reviews positive

4·Blackguards
91% match · Turn-Based, Tactical
62% of 3,922 reviews positive

5·X-COM: UFO Defense
90% match · Classic, Turn-Based Strategy
95% of 4,007 reviews positive

6·Worms
90% match · Classic, Turn-Based Strategy
83% of 707 reviews positive

7·Heroes® of Might & Magic® III - HD Edition
90% match · Classic, Turn-Based Strategy
79% of 25,057 reviews positive

8·Jagged Alliance Flashback
89% match · Turn-Based, Strategy
47% of 777 reviews positive

9·The Banner Saga 3
89% match · Turn-Based Tactics, Tactical RPG
78% of 3,111 reviews positive

10·Antisquad
89% match · Turn-Based, Turn-Based Strategy
52% of 298 reviews positive

11·Sonny
89% match · Turn-Based, RPG
56% of 535 reviews positive

12·Heroes of Might & Magic V
89% match · Turn-Based Strategy, Turn-Based
88% of 4,318 reviews positive

13·MASSIVE CHALICE
88% match · Turn-Based, Turn-Based Tactics
73% of 1,912 reviews positive

14·King's Bounty: The Legend
88% match · Turn-Based Strategy, Turn-Based
91% of 4,047 reviews positive

15·Fallout Tactics: Brotherhood of Steel
88% match · Turn-Based, Classic
79% of 2,955 reviews positive

16·Jagged Alliance 3
87% match · Turn-Based Tactics, Tactical
88% of 15,109 reviews positive · 2,364 playing

17·Halfway
87% match · Turn-Based, Strategy
72% of 1,018 reviews positive

18·Etherlords II
87% match · Turn-Based, Turn-Based Strategy
83% of 500 reviews positive

19·Disciples III - Renaissance Steam Special Edition
87% match · Turn-Based, Strategy
51% of 545 reviews positive

20·Disciples III - Resurrection
87% match · Turn-Based, Strategy
30% of 341 reviews positive

21·Fae Tactics
87% match · Turn-Based Tactics, Strategy
85% of 1,755 reviews positive

22·Gears Tactics
87% match · Turn-Based Tactics, Strategy
75% of 7,786 reviews positive · 48 playing

23·Ascension to the Throne
86% match · Turn-Based, Strategy
90% of 689 reviews positive

24·King's Bounty: Warriors of the North
86% match · Turn-Based Strategy, RPG
79% of 2,075 reviews positive
The closest matches to Jagged Alliance 1: Gold Edition on Steam are Silent Storm Gold Edition, Deadlock II: Shrine Wars, Etherlords, Blackguards, X-COM: UFO Defense. They rank highest because their Steam community tags overlap most with Jagged Alliance 1: Gold Edition's, and shared tags include Turn-Based Tactics, Turn-Based, Tactical RPG.
Every game is described by the tags Steam players vote on it. Rare, specific tags such as Turn-Based Tactics, Turn-Based, Tactical RPG count far more than catch-all ones like "Indie" or "Singleplayer", and each game is scored on how closely its whole tag profile matches Jagged Alliance 1: Gold Edition's. Popularity never affects the ranking.