Games like Snow Fortress 2
Games like Snow Fortress 2 include Garry's Mod, Aimlabs, Squad, Besiege, and PUBG: BATTLEGROUNDS. We matched them by the tags players give Snow Fortress 2 on Steam (FPS, Tower Defense, Building, Medieval, and Base Building): closest matches first, and among equally close ones the better-known games.

Garry's Mod
Shared: Building · Physics · FPS

Aimlabs
Shared: FPS · Shooter · Simulation

Squad
Shared: FPS · PvE · PvP

Besiege
Shared: Medieval · Building · Physics

PUBG: BATTLEGROUNDS
Shared: FPS · Shooter · PvP

GoreBox
Shared: FPS · Physics · PvE

How to Fish
Shared: FPS · Physics · Shooter

BONELAB
Shared: Physics · FPS · Shooter

Kingdom Two Crowns
Shared: Tower Defense · Building · Base Building

Rust
Shared: Building · PvP · FPS

Apex Legends™
Shared: FPS · Shooter · PvP

Space Engineers
Shared: Building · Physics · Base Building

Thronefall
Shared: Tower Defense · Medieval · Building

Battlefield™ 2042
Shared: FPS · Shooter · PvP

7 Days to Die
Shared: Base Building · Building · FPS

BONEWORKS
Shared: Physics · Shooter · FPS

Half-Life 2
Shared: FPS · Shooter · Action

Scrap Mechanic
Shared: Building · Physics · Base Building

Counter-Strike: Source
Shared: FPS · Shooter · PvP

WARDOGS
Shared: FPS · PvP · Shooter

Call of Duty®
Shared: FPS · Shooter · Action

Bodycam
Shared: FPS · Shooter · PvP

Destiny 2
Shared: FPS · PvE · PvP

s&box
Shared: Building · FPS · Shooter