MegaMek: Play BattleTech Online for Free

MegaMek is a free, open-source digital implementation of Classic BattleTech that lets you play online against other players or solo against an AI opponent. It has been in continuous development by volunteers since 2002 and covers the full published BattleTech ruleset more completely than any commercial product.

The Lance Builder on this site was built using MegaMek's MTF files — their database of every published BattleMech is the most comprehensive freely available resource for BattleTech data. The MegaMek project deserves proper credit and proper coverage. This article is both.

What MegaMek Actually Is

MegaMek is not a video game. It doesn't have a campaign mode, a story, or real-time action. It is a faithful digital implementation of the Classic BattleTech tabletop rules — the same rules in your box set, running on your computer. The hex grid, the record sheets, the initiative rolls, the heat tracking, the cluster hit tables — all of it is there.

What that means in practice: if you know how to play BattleTech at the table, you know how to play MegaMek. If you don't, MegaMek is actually a reasonable way to learn — the computer handles the bookkeeping and you can play at your own pace without a physical opponent.

MegaMek is three separate programs that work together:

• MegaMek — the game itself. Ground combat between BattleMechs, vehicles, infantry, and aerospace units on a hex grid.
• MekHQ — campaign management. Track your mercenary company between battles: pilot experience, 'Mech maintenance and repair, parts inventory, contract negotiation, and force management.
• MegaMekLab — the 'Mech designer. Build custom 'Mechs and vehicles from scratch following the official construction rules, or modify existing designs.

You can use any of these independently. Most people start with just MegaMek for online play and add MekHQ when they want to run a campaign.

Getting It

Download from megamek.games. The current stable release is what you want. It requires Java — the installer will tell you if you need to install it separately.

It runs on Windows, Mac, and Linux. Installation is straightforward: download, extract, run. There's no installer in the traditional sense — you extract a folder and run the executable inside it.

Playing Online

Online play works on a server-client model. One player hosts a server (or uses a public server) and other players connect to it.

Finding games: The MegaMek Discord server is where most active players coordinate. The MegaMek Discord has dedicated looking-for-game channels where you can post your availability and find opponents. Games are typically arranged in advance rather than drop-in — agree on era, force size, BV limits, and scenario before connecting.

Hosting a game: Start MegaMek, select "Host a New Game," configure your settings, and share your IP address with your opponent. If you're behind a home router you'll need to port-forward the MegaMek port (2346 by default) — your router's documentation covers how to do this. Alternatively, services like Hamachi can create a virtual LAN that avoids the port forwarding requirement.

Connecting to a game: Start MegaMek, select "Connect to a Game," enter the host's IP address and port. Done.

Playing Solo Against the AI

MegaMek includes a Princess bot — an AI opponent that plays BattleTech at a competent level. She's not going to fool anyone into thinking she's human but she'll challenge new players and she's available at 3am when you want to play and nobody else is online.

To play against Princess: start a game, add a bot player, assign her a force, and start. You can adjust her aggression and self-preservation settings. Higher aggression makes her attack more recklessly — useful for testing defensive positions. Lower self-preservation makes her fight to the last — useful for scenarios where you want the AI to hold ground.

Solo against Princess is genuinely useful for learning the game. You can pause at any point, undo moves you haven't committed yet, and play at whatever speed suits you. There's no opponent waiting for you to finish your turn.

The MegaMek Database

Every canon BattleMech, vehicle, infantry unit, and aerospace unit in the published BattleTech line is in MegaMek's database — over 3,700 'Mech variants alone. The database is maintained by volunteers who cross-reference the official sourcebooks and update it with each new Catalyst Game Labs release. It is, genuinely, the most complete and accurate BattleTech unit database freely available anywhere.

This is the database I used to build the Lance Command Console on this site. The MTF files (MegaMek's format for 'Mech specifications) contain every weapon, heat sink, armour value, and movement stat for every published variant. The faction availability data comes from the Master Unit List, which MegaMek also integrates with.

If you find a discrepancy in the Lance Builder — a 'Mech with wrong stats or incorrect BV — the first place to check is MegaMek's own entry for that variant. Their database is the authoritative reference.

MekHQ: Running a Campaign

MekHQ is the campaign management layer that turns individual MegaMek battles into a connected mercenary career. It handles:

• Pilot tracking — experience gained in battles, skill improvements, injuries, deaths
• 'Mech maintenance — battle damage tracked between missions, parts required, repair time
• Parts inventory — maintain a stockpile of spare parts, buy and sell equipment
• Contracts — negotiate with factions for missions, manage your reputation
• Finance — payroll, contract payments, equipment purchases
• Personnel — MechWarriors, technicians, medics, administrators

MekHQ integrates directly with MegaMek — you set up a battle in MekHQ, play it in MegaMek, and the results (kills, damage, pilot injuries) feed back into MekHQ automatically. It's a genuinely deep campaign system and the closest thing to a full BattleTech RPG management game currently available.

AtB (Against the Bot) is a solitaire campaign framework built into MekHQ that generates opponents and contracts procedurally, allowing full solo campaign play without a human opponent. If you want to run a mercenary campaign on your own schedule, AtB is worth understanding.

MegaMekLab: Building Custom 'Mechs

MegaMekLab is a 'Mech construction tool that implements the official BattleTech construction rules. You pick a weight class, choose an engine, allocate armour, mount weapons, and the tool validates that your design follows the rules. It generates a record sheet you can print for tabletop use or export for use in MegaMek.

Useful for: custom campaign 'Mechs, homebrewed variants for house rules games, understanding why certain canon designs make the choices they do, and scratching the "what if I put an AC/20 on a Locust" itch that every BattleTech player has eventually.

Contributing to MegaMek

MegaMek is an open-source volunteer project hosted on GitHub. The people maintaining it are doing it in their spare time because they love BattleTech. If you use MegaMek regularly, consider contributing:

• Bug reports — the GitHub issue tracker is how problems get fixed
• Data corrections — if a 'Mech has wrong stats, a pull request fixing it is welcome
• Code contributions — the project is Java-based and always needs developers
• Financial support — the project has a Patreon for server costs
• Community — being active in the Discord, helping new players, writing documentation

The BattleTech community benefits enormously from MegaMek existing. It lowers the barrier to entry for online play, preserves the complete ruleset in an accessible form, and maintains the most comprehensive 'Mech database available. It deserves support proportional to that contribution.

Getting Started Checklist

1. Download MegaMek from megamek.games
2. Install Java if prompted
3. Join the MegaMek Discord and read the getting-started channels
4. Run a game against Princess solo to learn the interface
5. Post in the Discord looking-for-game channel to find your first online opponent
6. When you're ready for a campaign, add MekHQ and look up the AtB guide in the Discord

The learning curve for the interface is real — MegaMek is not a polished commercial product and it shows in the UI. Give it a session or two before deciding whether it's for you. The underlying game it implements is worth the patience.