On Mars vs Terraforming Mars: Which Should You Buy?

In On Mars, you're running a company building the first real colony, and your attention is split between an orbiting station and the surface below. A shuttle bounces between the two, and if you're not on the right side when it leaves, you pay for the ride. You're hauling resources, training colonists, sending out rovers, and timing your buildings so the colony grows on your turn. Every rule serves the theme, so the colony you build actually feels earned, and nothing in the design is a loose bolt. Everything connects to everything, and when it finally locks together, the payoff is huge.

Terraforming Mars comes at the planet from a completely different angle. You're a corporation raising the temperature, flooding in oceans, and seeding oxygen until Mars hits habitable, and you do it all through cards. Over 200 of them, each one another part bolted onto your economy. Where On Mars asks you to master one big machine the game hands you, Terraforming Mars is about building your own machine from scratch and watching it turn a red rock blue. The engine-building here is some of the most satisfying in the hobby, and that's not a small claim.

Both boxes say heavy, but they don't mean the same thing by it. On Mars sits around 4.6 out of 5 on the BoardGameGeek weight scale, and that number is not lying to you. Reviewers openly admit it took a full play before they understood how the subsystems feed each other, so treat your first game as tuition. Casual players will drown, and I mean that kindly. This is a box for groups who have already cut their teeth on lighter euros and treat a four-hour thinky puzzle as the reward, not the punishment.

Terraforming Mars is heavy too, but it's a friendlier kind of heavy. Most of the complexity lives on the cards, and cards explain themselves one at a time. The catch is downtime: a big hand invites analysis paralysis, an early leader tends to snowball, and a couple of slow turns can drag the table. Still, a strategy-curious newer player can survive their first game of Terraforming Mars and want another one. I would not say the same about On Mars.

Terraforming Mars wins the variety contest without breaking a sweat. Over 200 project cards and 12 corporations means setups genuinely don't repeat, and one reviewer put 20 games in and said no two felt the same. That tracks with its spot at number nine on BoardGameGeek. Player count matters, though. Two players drags, five ends before your engine really sings, and three or four is the sweet spot. One fair warning on the box itself: component quality is rough for the price, and those little plastic cubes slide everywhere the moment someone bumps the table. Grab a playmat or some baggies and you'll forgive it.

On Mars earns its replays a different way, through depth rather than variety. The systems lock together beautifully once it clicks, so groups keep coming back to play it better, not just to see new cards. It sings at 3-4 players, where blocking and resource grabs get properly tense, and it limps a bit at two. Just know what you're committing to. It's long, often three hours or more, and it's a total table hog with side boards everywhere. You'll need real space and real time, every single play.