Games like Cannon Island
Games like Cannon Island include Foundation, Kingdoms and Castles, Banished, Manor Lords, and RimWorld. We matched them by the tags players give Cannon Island on Steam (City Builder, Cute, Sandbox, Relaxing, and Base Building): closest matches first, and among equally close ones the better-known games.

Foundation
Shared: City Builder · Sandbox · Management

Kingdoms and Castles
Shared: City Builder · Management · Sandbox

Banished
Shared: City Builder · Colony Sim · Sandbox

Manor Lords
Shared: City Builder · Base Building · Sandbox

RimWorld
Shared: Base Building · Sandbox · Colony Sim

Cities: Skylines II
Shared: City Builder · Sandbox · Management

Dwarf Fortress
Shared: City Builder · Base Building · Sandbox

Prison Architect
Shared: Sandbox · Base Building · City Builder

Going Medieval
Shared: Base Building · City Builder · Colony Sim

Cities: Skylines
Shared: City Builder · Sandbox · Management

Timberborn
Shared: City Builder · Sandbox · Colony Sim

Ostriv
Shared: City Builder · Management · Base Building

Frostpunk
Shared: City Builder · Colony Sim · Base Building

Fabledom
Shared: City Builder · Sandbox · Relaxing

Infection Free Zone
Shared: City Builder · Base Building · Management

The Wandering Village
Shared: City Builder · Management · Cute

Workers & Resources: Soviet Republic
Shared: City Builder · Base Building · Management

Against the Storm
Shared: City Builder · Base Building · Management

Oxygen Not Included
Shared: Base Building · Colony Sim · Sandbox

Kingdoms Reborn
Shared: City Builder · Base Building · Colony Sim

Stronghold Crusader HD (2012)
Shared: City Builder · Base Building · Colony Sim

Town to City
Shared: City Builder · Cute · Relaxing

Empires of the Undergrowth
Shared: City Builder · Base Building · Sandbox

Planet Zoo
Shared: Management · Sandbox · City Builder