In 2006 Microsoft released a modified version of the source code along with most game assets (i.e. everything needed to compile the game without networking support and without all the art) under a Shared Source license in order to demonstrate its XNA Build system.
Carver V, a planet previously held by House Liao, but at the time of the storyline's start, House Steiner and House Davion have also laid claim to a few territories, killing Mandarin Cho, Liao ruler of the planet, in combat. The House forces on Carver V remained tense, but otherwise avoided any direct military action that would endanger the relatively peaceful situation. However, when a suspiciously well-equipped bandit force threatens Steiner territory, the chief military representative of House Steiner Colonel David Renard proposes quite an unusual countermeasure - a "neutral" mercenary force.
In Campaign 1, the player is under the command of Steiner Colonel David Renard and starts with a number of easy tasks (attacking bandit encampments and reclaiming facilities that have been overrun). Suspicions arise of the bandits' allegiance when a captured mobile HQ reveals that they are headed by one Chung Vong, a former Liao officer. These sentiments are confirmed when Liao forces grant refuge to a fleeing bandit convoy on the Steiner-Liao border. In response to this and despite protests from Steiner's Ambassador Yi, Colonel Renard orders the player into Liao territory, shattering the tentative peace between local Liao and Steiner forces and beginning a new series of operations against Liao forces. The final mission of the campaign takes the player to the remote Little Bear island to destroy the last of the bandit forces, their HQ, and their leader. Despite the player's overwhelming success, Colonel Renard ends his contract with the mercenaries and hints at his motives with the blunt remark, "Do this and get out. I've got plans for Carver V and you don't want to be part of them."
Campaign 2 begins with a twist as the player is now in the employ of its former enemy - House Liao. The player is under the command of Mandrissa Anita Cho, the widow of Mandarin Cho, and her son, Captain Jason Cho. Mandrissa is seemingly ill with a terminal disease, and her last wish before she dies is for her son, Jason, to rule Carver V. For the first mission, the player is tasked with liberating a remote Steiner prison camp containing political prisoners, better known as the Gulag (a reference of Soviet Gulag labor camp system). The mission starts with Renard saying "So, you've betrayed me too..." and giving orders to destroy the camp, a fact that disgusts even normally-indifferent Lieutenant Diaz, the player's tactical advisor. This mission also marks the first appearance of Baxter, the commander of partisan forces on planet, who dispatches transports to recover survivors. In the following missions, the player is tasked with various covert ops missions, including the instigation of conflict between Steiner and Davion troops, a deployment deep into enemy lines to dispatch Steiner-held orbital guns, and an encounter with a couple of Davion bondsmen (spoils from Operation Bulldog) on Carver V's moon during a mission to destroy the Hyperpulse Generators: the only immediate means of communication to other worlds.
But despite the player's concurrent successes, it seems that Jason Cho is an incompetent commander, as Liao forces are regularly served beatings under his command and are forced to negotiate a truce with House Steiner. Colonel Renard agrees, seeing as both houses have a mutual enemy, the Davions, but only if Cho agrees to one condition - the mercenaries must die. Jason gladly agrees, and player is forced to flee before advancing Steiner forces, and by securing an abandoned base, manages to beat the Steiner troops back. Jason then steps forward to personally deal with the mercenaries, and is killed by the player. Outraged by the death of her son and only heir, Mandrissa Cho sends a reprisal force of Liao units which are defeated with the help of Baxter, who once again sends his forces to help the mercenaries.
In Campaign 3, it is revealed that Baxter and Davion commander Major Kelly have allied, as Davion is not against an independent Carver V. In exchange for revenge and Clan technology, the player fights on the rebel/Davion side, defending the city of Bannickburg, eliminating heavily defended Steiner and Liao bases, and even destroying the Liao palace (though Mandrissa Cho personally commits suicide after her elite guard is crushed). The fight for Carver V is finished when the player defeats a crazed Colonel Renard (who appears in a jump-capable Atlas, which is unusual as Atlas 'mechs cannot be equipped with jump-jets in MC2) and destroys the Steiner High Command on planet.
The Campaign ends with Archon (Katrina Steiner) mourning Colonel Renard's death, Baxter becoming a President of Carver V, now renamed Liberty, and the mercenary team returning back to the Periphery - raising their price on MercNet. "Peace has been restored on Carver V by an unlikely source - a mercenary commander."
MechCommander 2 features 29 'Mechs each with their own strengths and weaknesses. Generally, the lighter 'Mechs scout while the heavier 'Mechs fight. Depending on which side the mercenary MechCommander works for, different 'Mechs would be available for purchase and salvage after combat missions. The 'Mechs from each House also display different characteristics; heavy firepower for House Steiner 'Mechs, agility and advanced sensors for House Liao 'Mechs, and superior-quality 'imported' Clan 'Mechs for House Davion.
- House Steiner 'Mechs
- Razorback (Light - 30 tons)
- Hollander (Light - 35 tons)
- Hunchback (Medium - 50 tons)
- Bushwacker (Medium - 55 tons)
- Shootist (Heavy - 70 tons)
- Zeus (Assault - 80 tons)
- Highlander (Assault - 90 tons)
- Atlas (Assault - 100 tons)
- House Liao 'Mechs
- Anubis (Light - 30 tons)
- Raven (Light - 35 tons)
- Sha Yu (Medium - 40 tons)
- Starslayer (Medium - 50 tons)
- Men Shen (Medium - 55 tons)
- Catapult (Heavy - 65 tons)
- Lao Hu (Heavy - 75 tons)
- Cyclops (Assault - 90 tons)
- House Davion 'Mechs
- Wolfhound (Light - 35 tons)
- Enfield (Medium - 50 tons)
- JagerMech (Heavy - 65 tons)
- Clan 'Mechs ('Imported')
- Kit Fox [Uller] (Light - 30 tons)
- Cougar (Light - 35 tons)
- Shadow Cat (Medium - 45 tons)
- Stormcrow [Ryoken] (Medium - 55 tons)
- Mad Dog [Vulture] (Heavy - 60 tons)
- Summoner [Thor] (Heavy - 70 tons)
- Timber Wolf [Mad Cat] (Heavy - 75 tons)
- Blood Asp (Assault - 90 tons)
- Miscellaneous 'Mechs (Bandits)
- Fire Ant (Light - 30 tons)
- UrbanMech (Light - 30 tons)
- Equipment in MechCommander 2 and its mods
- BattleMechs in MechCommander 2 and its mods
- Vehicles in MechCommander 2 and its mods
- Characters in MechCommander 2 and its mods
- MechCommander 2 Source code
- TCLN Gaming League
- MechCommander 2 - Official Website
- wolfman's missions - unofficial Expansion Pack, Missions and Campaigns
- MechCommander Omnitech - unofficial project with revamped source code, new mechs and campaigns