Terraforming Mars vs Underwater Cities: Which Should You Buy?

In Terraforming Mars, you're a corporation making the planet livable: raising the temperature, flooding in oceans, seeding oxygen until Mars hits habitable. You do it all through cards, more than 200 of them, and each one bolts another part onto your economy. The theme and mechanics actually line up here, which is rarer than it should be. Every action feels like it's genuinely changing Mars, and the engine you build from scratch is some of the most satisfying in the hobby. One reviewer at Meeple Mountain put 20 games in and said no two felt the same. That's the whole hook, and it holds.

Underwater Cities plays smaller and squeezier, in a good way. You're building domed cities on the seafloor, linking them with tunnels and propping them up with farms, labs, and desalination plants. Every turn you play one of three cards onto an action slot around the board. Match the card's color to the slot and you get both the action and the card's bonus. Miss, and you only get the action. With just three cards in hand, that tiny color-matching decision is the whole game, and it's a real, tense choice every single turn. The catch: your engine only pays out three times all game (really twice in a way that matters), so if you're expecting a snowballing tableau, it can feel a little anemic. Where Mars sprawls, this one clenches.

Terraforming Mars is the heavier teach. It's a full heavy euro with a huge card pool, and a first game means walking new players through a deep card-driven economy while they're holding a hand full of options. That heavy hand invites analysis paralysis, an early leader tends to snowball, and it flat out punishes anyone who wanted something light and quick. Save it for a group that actually asked for a two-hour brain workout. The one mercy is the theme, which carries the teach beautifully. Everyone understands heating up a planet.

Underwater Cities sits a notch lighter at medium-heavy, and the core loop is genuinely simple to explain: play a card, pick a slot, try to match the color. The depth comes from the squeeze, not from a mountain of rules, so it's the gentler on-ramp for a first play. That said, don't mistake simpler for faster. The analysis paralysis here is brutal in its own right, because every one of those three-card decisions matters so much, and an AP-prone group of four can drag past two hours.

Variety is where Terraforming Mars runs away with it. Over 200 project cards and 12 corporations means the game genuinely reshuffles every play, and it sits at number nine on BoardGameGeek for a reason. Player count matters, though. Two-player games drag, five-player games end before your engine really sings, and three or four is the sweet spot. Fair warning on the box itself: the components are rough for the price, and those little plastic cubes slide everywhere. Grab a playmat or some baggies and you'll forgive it.

Underwater Cities flips that player-count math completely. It shines solo, with a meaty advanced solo board, and it's tense and sharp at two, with barely any elbows from other players. At four, the three-turns-per-round rhythm gets stop-start and overstays its welcome. Its staying power comes from the puzzle rather than spectacle, because the theme never really comes alive. Your grand ocean city ends up as colored discs and domes, and the art leans weirdly corporate, so it's not a game you show off. It's one you quietly chew on, and watching your connected network finally pay off feels great.