Games like Harpoon
Games like Harpoon include Cat Goes Fishing, Escape From Duckov, UMIGARI | ウミガリ, DAVE THE DIVER, and Deep Rock Galactic. We matched them by the tags players give Harpoon on Steam (Exploration, Top-Down Shooter, Sailing, Hunting, and Fishing): closest matches first, and among equally close ones the better-known games.

Cat Goes Fishing
Shared: Fishing · Exploration · 2D

Escape From Duckov
Shared: Top-Down Shooter · Exploration · Shooter

UMIGARI | ウミガリ
Shared: Exploration · Fishing · Hunting

DAVE THE DIVER
Shared: Exploration · Fishing · Casual

Deep Rock Galactic
Shared: PvE · Exploration · Shooter

DREDGE
Shared: Exploration · Fishing · Sailing

Minishoot' Adventures
Shared: Exploration · Top-Down Shooter · Top-Down

Windrose
Shared: Exploration · PvE · Sailing

Depth
Shared: Shooter · Underwater · Hunting

How to Fish
Shared: Fishing · Shooter · Indie

Insect Swarm
Shared: Top-Down Shooter · Shooter · Exploration

Army of Ruin
Shared: Exploration · Top-Down Shooter · Shooter

ABZU
Shared: Exploration · Underwater · Casual

Rain World
Shared: Exploration · 2D · Indie

Way of the Hunter
Shared: Exploration · Hunting · Shooter

12 is Better Than 6
Shared: Top-Down Shooter · Shooter · 2D

SYNTHETIK 2
Shared: Top-Down Shooter · Shooter · Top-Down

Hollow Knight: Silksong
Shared: Exploration · 2D · Indie

Sailwind
Shared: Sailing · Exploration · Fishing

Hollow Knight
Shared: Exploration · 2D · Indie

RUNNING WITH RIFLES
Shared: Top-Down Shooter · Top-Down · PvE

Animalia Survival
Shared: Exploration · Hunting · PvE

Fallout 4
Shared: Exploration · Shooter · Atmospheric

Terraria
Shared: Exploration · 2D · Indie