Games like Event Horizon
Games like Event Horizon include Warhammer 40,000: Inquisitor - Martyr, Space Pirates And Zombies 2, Between the Stars, Space Pirates and Zombies, and Bastion. We matched them by the tags players give Event Horizon on Steam (Action, Indie, RPG, and Space): closest matches first, and among equally close ones the better-known games.

Warhammer 40,000: Inquisitor - Martyr
Shared: Action · RPG · Indie

Space Pirates And Zombies 2
Shared: Action · Space · Indie

Between the Stars
Shared: Action · RPG · Space

Space Pirates and Zombies
Shared: Action · Indie · Space

Bastion
Shared: Indie · Action · RPG

Hades
Shared: Indie · Action · RPG

Starcom: Nexus
Shared: Space · RPG · Action

Dust: An Elysian Tail
Shared: Action · Indie · RPG

Star Valor
Shared: Action · Space · RPG

Mass Effect (2007)
Shared: RPG · Action · Space

Warframe
Shared: Action · RPG · Space

Mass Effect™ Legendary Edition
Shared: RPG · Space · Action

Rebel Galaxy
Shared: Space · RPG · Action

Hades II
Shared: Action · RPG · Indie

The Wind Road
Shared: Action · RPG · Indie

Dungeon Munchies
Shared: Action · Indie · RPG

Deliver Us The Moon
Shared: Indie · Action · Space

Pyre
Shared: Indie · RPG · Action

UnEpic
Shared: Indie · RPG · Action

Starpoint Gemini 2
Shared: Space · RPG · Action

Trailmakers
Shared: Action · Space · Indie

Black Myth: Wukong
Shared: Action · RPG

The Incredible Adventures of Van Helsing
Shared: RPG · Action · Indie

ICEY
Shared: Action · Indie · RPG