Terraforming Mars but severely damp, considerably tighter, and infinitely more stressful.

Right, if you absolutely adore Terraforming Mars—pushing cubes, building economies, agonizing over resources—but secretly harbor a deep resentment for the sheer physical ugliness of the original components and the chaotic length, you need to dive directly into Underwater Cities. Designed by Vladimir Suchy, this is essentially a masterclass in how to build a highly complex, heavily constrained engine builder without absolutely bloating the runtime into a five-hour slog. You have explicitly swapped the dusty red orbital colonies for massive, incredibly tense submarine domes.

The core mechanic that entirely elevates this game is the flawless integration of card play and worker placement. On your turn, you simply place an action token on a slot on the central board to gather resources or construct a terrifying underwater tunnel. But crucially, you must simultaneously play a card from your hand. If the color of the card physically matches the color of the action space you just took, you immediately trigger the card's incredibly powerful bonus ability! If the colors do not match, you simply discard the card into an absolute void of complete waste.

This single, brilliantly simple rule creates an agonizing, brain-melting puzzle almost immediately. You stare at a hand containing three green cards that offer utterly spectacular economic engine boosts, and you look at the board and realize every single green placement spot has just been aggressively blocked by your opponent. You are forced to wildly compromise! Do you take a sub-optimal yellow action just to trigger the green card? Or do you take the highly powerful green action on the board and physically throw away your best card entirely just to afford it? It is sheer, unadulterated tension.

Family Session vs. Hardcore Gamers

Is this the perfect family game for a Sunday afternoon? Absolutely not. Unless your extended family actively enjoys intense, completely silent mathematical optimization over a tight three-hour period. It shares heavily with Terraforming Mars in the sense that everyone is frequently staring predominantly downward at their own sprawling personal player board, entirely ignoring the table conversation. It is an absolute heavyweight champion designed specifically for dedicated Euro-gamers who thrive on highly constrained, aggressively tight resource management.

Pros:

• The color-matching card mechanic provides an agonizingly tight and universally brilliant tactical puzzle.
• Scaling the economy from a single dome to a massive sprawling underwater network feels deeply satisfying.
• It physically plays much tighter and feels noticeably more streamlined than Terraforming Mars.

Cons:

• The base game essentially requires the expansion to unlock the vastly superior dual-layered player boards.
• Player interaction is strictly limited entirely to aggressively blocking placement spots.
• The physical card quality is slightly thin and they aggressively demand to be carefully sleeved.

Final Verdict: Buy it yourself. It seamlessly perfects the heavily addictive engine-building loop. If you want profound strategic depth and deeply satisfying combo-building without having to deal with chaotic asteroids hitting your base, this is an absolute mandatory upgrade to your collection.