What is a space sim? Space sim, space MMO and space survival explained

A space sim (space simulation game) is a game that recreates flying and operating spacecraft with some degree of physical realism: how the ship moves, how its systems work, how you navigate and how big space is. The more of those it takes seriously, the more “sim” it is.

The term is used loosely. Players call almost any game with a cockpit a space sim, and a lot of arguments in the genre are really arguments about where a game sits on that scale.

The three flight models

How a ship moves is the first thing that separates a space sim from a space shooter.

Flight model	How the ship behaves	What it asks of you	Where you find it
Arcade	Like an aircraft: point the nose and the ship goes there; there is a top speed	Aiming and reflexes	Many space action and exploration games
Newtonian with assists	Real inertia: you keep drifting until you thrust the other way. A flight computer smooths it so you can fight and dock	Energy management and control; the option to switch the assist off	Most combat-oriented space sims
Orbital mechanics	You do not “fly” so much as change orbits: burns, transfers, spheres of influence	Planning and patience	Rocketry and orbital games

Newtonian flight with assists is the compromise most combat-oriented space sims choose. Pure orbital flight is the most realistic, but it is hard to have a dogfight when changing direction means planning a burn.

What “realism” means in a space sim

Realism is not one thing. It breaks down into four dimensions, and games pick different mixes:

• Scale. How big planets are and how far apart they sit. A few games recreate a galaxy at true scale; most compress distances so travel stays playable, which is what COLONIZED does with one lore astronomical unit equal to 15 million km.
• Physics. Inertia, gravity, atmosphere and how they affect flight.
• Systems. Power, heat, components, fuel, damage to specific parts of the ship.
• Time. Whether travel takes real time and whether the universe moves on (orbits, day and night) when you are not looking.

A game can be very realistic in one dimension and loose in another. A universe at true scale with arcade flight is as common as precise flight in a compressed system.

Space sim, space MMO, space survival

Three labels that overlap but answer different questions:

Label	The question it answers	Example of each, alone
Space sim	How do ships fly and work?	A single-player game focused on flight and ship systems
Space MMO	Who else is in the universe?	A persistent online universe shared by many players
Space survival	What keeps you alive?	Oxygen, resources, crafting and shelter as the core loop

Many current games combine two of them, and a few aim at all three. COLONIZED is one of those: a space survival MMORPG with realistic space simulation. We explain the survival and MMO sides in what is a survival MMO and MMO vs MMORPG.

Walking around the ship

For a long time, space sims stopped at the cockpit. The ship was a vehicle; you never stood up. The genre has been moving the other way: players want to walk from the cockpit to the bunk, and big ships increasingly have interiors you can walk through. It changes what a ship is. A ship you live in is a home and a base, not only a vehicle, which is why it matters so much in survival games set in space. We explain what it takes in space games where you can walk inside your ship.

Where COLONIZED fits

COLONIZED is a space survival MMORPG for PC, built in Unreal Engine 5, with realistic space simulation: ships specified in metres and tonnes, weapons in sizes from S1 to S8, and a star system, Aurin, whose catalogue gives every body a real radius and a Keplerian orbit, with distances compressed so the whole system fits in the engine. We explain that method in how to simulate a solar system at scale. Ship flight is in development, and we will show how it feels when it can be played, not before. Applications for the closed alpha are open; its first wave is planned for winter 2026-2027.

Go deeper: eight things a good space sim gets right, space survival versus space sim and walking inside a moving ship in multiplayer.