How to Play Terraforming Mars Online

By the Tavernly team · 1 November 2026

Terraforming Mars is a board game for 1 to 5 players about waking a planet, and you can play it online in a few ways. This guide shows how to play Terraforming Mars online with Board Game Arena, the Steam and phone apps, or our free browser alternative. We make After the Ash on Tavernly, a free browser alternative.

The short answer

Browser: Board Game Arena plays Terraforming Mars with a free account; no Premium is needed.

Apps: Terraforming Mars is on Steam, the App Store and Google Play.

Free browser alternative: After the Ash on Tavernly has friends, bots and a coached lesson.

Which way is best to play Terraforming Mars online?

Board Game Arena has browser tables, while the official app offers Steam and phone play. After the Ash on Tavernly offers free browser games with bots or friends. Choose its coached lesson for a guided first game, or play at your pace with turn notifications.

You want to…	Option
Join browser tables	Board Game Arena
Download an app	Steam, App Store, Google Play
Face bots or invite friends	After the Ash on Tavernly
Follow a coached lesson	After the Ash on Tavernly

Board Game Arena: browser tables

Board Game Arena lists Terraforming Mars as a browser game for 1 to 5 players, with a duration of 54 minutes. Its complexity is 4 of 5. A free account is enough to join and host tables; no Premium is needed. The panel lists draft and beginner options.

You need: a browser and a Board Game Arena account.

Open the game panel. Follow the Terraforming Mars panel link.
Join a table with a free account. No Premium is needed to host. The Board Game Arena FAQ lists the table rules.
Pick table options. The panel lists a draft option and a beginner option. Prelude and Colonies are listed expansions.
Play solo. Board Game Arena lists a solo variant with 14 rounds.

The official app: Steam and phone stores

The official Terraforming Mars app is published by Twin Sails Interactive. Steam supports Windows and Mac, with single-player and online multiplayer listed. The App Store lists online or offline multiplayer and a solo challenge, and the app also has a Google Play listing.

You need: the relevant store and a device it supports.

Open the Steam listing. Find Terraforming Mars on Steam for Windows or Mac. Its list price is $19.99; sales can change it.
Open the App Store listing. Terraforming Mars in the App Store lists a price of $8.99. Its listed expansions are extra purchases.
Open the Google Play listing. Follow Terraforming Mars on Google Play for that phone app.

A Terraforming Mars alternative: After the Ash on Tavernly

After the Ash on Tavernly is a free browser game for 1 to 5 players aged 13 or over. A game takes about 60 to 90 minutes with 2 players. You can play with bots or friends, or follow a coached lesson.

You need: a browser.

Start a bot game. Open the page and enter your birth month and year. Under Play against bots, choose Opponents, Bots and Cards and draft, then press Play now.

The After the Ash page offers four ways to start: Play against bots, With friends, At your pace and Beginner. — The After the Ash page: bots, friends, your own pace, or a coached first game.

Invite friends. Under With friends, press Start now, choose seats, then press Start a private table. Send the Share invite link; press Start now: bots take the empty seats when ready.

The waiting room of a private table, with a share link, one host seat and three empty seats that bots can take. — The waiting room of a private table. Share the link; bots take any seat that stays empty.

Choose your pace. Reserve saves a table for later. Find players, under At your pace, is for real people playing at their own pace, with turn notifications.
Make your opening choice. Keep one guild house and select project cards. Each card you keep costs 3 coins.

The first-year screen: two guild houses and ten project cards, with two cards picked and the Keep button showing what is left. — The first year: keep one house and any of your 10 cards, 3 coins each.

Find your turn. Read the turn banner, then choose one or two actions. The Pass button ends your actions for the year.

The After the Ash board in year 1: the Vale map, three tracks, six resources, standard projects, milestones and awards. — Your first turn: the Vale in the middle, the tracks on the left, the projects on the right.

Learn by playing

Open the lesson. Under Beginner, press Learn by playing.
Follow the coach. Read the notes and make the requested moves.
Continue through the chapters. The coached first game has 7 chapters, with 60 notes and 18 moves you make.

Learn the rules

These are the rules of After the Ash on Tavernly, our version.

Pick a house and cards. A guild house gives your starting resources. Keep one of two houses and any of 10 project cards, paying 3 coins per card. This choice replaces the first year's buying phase.
Read the tracks. The Vale is the map of 61 hex spaces. Fill warmth from -30 to +8 degrees, bloom from 0 to 14, and springs from 0 to 9. Warmth moves in 2-degree steps. Each rise earns 1 renown: income each year and points at the end.
Take a turn. Choose one or two actions, or pass for the year. Your resources are coins, stone, brass, seeds, power and heat. Each has stock, which you hold, and production, which you gain yearly. Renown starts at 20, or 14 solo.
Play a card. Pay its cost and meet its track or tag requirements; tags mark card categories. Stone pays 2 coins toward building cards; brass pays 3 toward sky cards. A work acts once and stays. An active card gives an ongoing effect or yearly action. An event acts once, then turns face down.
Choose a standard project. These repeatable actions cost coins: Sell cards costs 0 and pays 1 per discarded card. A water wheel costs 11 for 1 power production; a falling star costs 14 for one warmth step. A spring costs 18, a grove 23, and a town 25 with 1 coin production.
Place a tile. Springs occupy empty spring spaces. Groves occupy empty land beside your tiles and raise bloom. Towns occupy land away from other towns. Collect the printed bonus and 2 coins per neighboring spring.
Spend seeds or heat. Turn 8 seeds into a grove, or 8 heat into one warmth step.
End the year. After everyone passes, power becomes heat and production pays resources; coin income includes renown. Move the first-player mark one seat. For the next buying phase, draw 4 cards and pay 3 coins per card kept.
Finish the game. Full tracks after production end the game. Spend remaining seeds on groves, without bloom or renown, then count points. Most points wins; coins break ties. Solo lasts 14 years: fill every track to win.

Source	Points	Detail
Renown	1 each	Your final renown
Milestones	5 each	Achievements claimed for 8 coins; 3 maximum
Awards	5 first, 2 second	Fund scoring contests for 8, 14, then 20 coins
Groves	1 each	Groves you own
Towns	1 per adjacent grove	Any owner's groves count
Cards	Printed points	Add your card points

Tips and warnings

Budget for keeping cards. Each project card you keep costs 3 coins before you pay to play it.
Check tags before spending materials. Stone pays toward building cards; brass pays toward sky cards.
Look beside springs. Placing a tile earns 2 coins for each neighboring spring.
Remember active cards. Their actions can be taken once per year.
Watch the solo limit. In our version, you have 14 years to fill all three tracks.
Start with the coached lesson. Before inviting friends, press Learn by playing under Beginner for a coached first game.

Questions people ask

Do I need to download anything?

Terraforming Mars is available through Board Game Arena in your browser, and through the Steam and phone apps. After the Ash on Tavernly also runs in your browser. You do not need a download for either browser option; Steam supports Windows and Mac.

Can I play Terraforming Mars online for free?

You can join and host Terraforming Mars tables on Board Game Arena with a free account; no Premium is needed. After the Ash on Tavernly is free browser play with no sign-up. Its start cards offer bots, friends, play at your pace and a lesson.

Can I play alone or against the computer?

Terraforming Mars has a 14-round solo variant on Board Game Arena, and Steam lists single-player play. After the Ash on Tavernly lets you choose 0 opponents for solo, or Easy, Medium or Hard bots. In our version, the solo game lasts 14 years.

Can I play with friends?

Terraforming Mars has browser tables on Board Game Arena, and Steam lists online multiplayer. In After the Ash on Tavernly:

Create a table. Choose With friends, then Start now and Start a private table.
Send the invitation. Press Share invite and send the link.
Start when ready. Bots can take empty seats.

Can I play on a phone?

Terraforming Mars has listings in the App Store and Google Play. The App Store lists online or offline multiplayer and a solo challenge. After the Ash on Tavernly is a browser option. The App Store price is $8.99, with expansions sold separately.

How many players?

Board Game Arena lists Terraforming Mars for 1 to 5 players. After the Ash on Tavernly also supports 1 to 5 players. For a private table, choose the number under Seats at the table. One seat gives you a game on your own.

How long does a game take?

Board Game Arena lists a duration of 54 minutes for Terraforming Mars. After the Ash on Tavernly takes about 60 to 90 minutes with 2 players. You can also choose At your pace, where real people play when they like and receive turn notifications.

Sources

We did not test a phone, and we did not read the Google Play price.

After the Ash is not affiliated with or endorsed by the owner of Terraforming Mars. Terraforming Mars is a trademark of its owner. As an Amazon Associate we earn from qualifying purchases. If you want the physical game, here is Terraforming Mars on Amazon.