These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
It doesn't seem like a broken base so much as two entirely different bases in the same series. There aren't many fans of both the original AND the sequel.
It's quite simple - Supreme Commander 2 is centred on the tactical scale of combat instead of strategical one, on which were Supreme Commander and Total Annihilation centred. So people who played it because they wanted to play the second part of TA's successor were disappointed by the decrease in scale, but overall the game is still very good and thus people who played it without comparing it to its predecessors were satisfied.
Fridge Logic: It's a good thing the enemy commanders you face are all constrained in what units they can build in the same way your superiors limit you. Missions would be over very quickly otherwise. They do like to throw curveballs, though, like the UEF mission which suddenly and with almost no warning pits you against a Cybran Monkeylord while you have nothing on its level. Good times.
The reason the Seraphim are trying to destroy humanity is because they believe that only one race may achieve perfection through the Way. However, most of the human society rejects the Way and only the Aeon preach and try to spread it. Wouldn't it make more sense to just kill off the Aeon instead of allying with them and trying to kill everyone else?
It's All There in the Manual, the Seraphim's first contact with humanity came well before the events of either game, as the humans nuked a peaceful Seraphim colony. This troper would be fairly pissed if it was his colony being nuked.
Game Breaker: Since balance in Supreme Commander was something of an ongoing issue, quite a number of them:
The release version included balance issues that had been identified in the beta but not actually addressed, including the Cybran Mantis being ludicrously overpowered in the early game and the UEF Broadsword gunship likewise in the late game; both were nerfed repeatedly.
This only really let the ridiculousness of the Aeon become apparent, though; typically having the best or at worst the second best of every unit type. Aeon were all but impossible to beat on water maps, trading the useless deck gun of other faction subs for a second torpedo attack and having a basic T1 tank that was amphibious; they also had a missile defence which couldn't be overwhelmed at all, a T3 artillery which was pinpoint accurate and fired twice, and the Harbinger, a Siegebot which had the best cost versus damage of any unit in the entire game. The Aeon superiority on maps with water was at one point so severe that all water maps were removed from competitive play.
Just... don't talk about the Aeon Restorer AA gunship. Just don't. Cheapest T3 gunship by an absurd amount, toughest T3 gunship, fastest T3 gunship and the only T3 gunship to have proper AA weapons (letting you save on ASF costs)? Their durability and versatility makes fact that they have only half the air-to-ground firepower of the Wailer and the Broadsword practically a non-issue, especially considering how much cheaper they are.
The ACU destruct nuke used to be a completely normal nuke; it was nerfed because every game was ending in draw-by-combombing.
AA weapons used to have no priority system of any kind, leading to a common tactic of building a gigantic number of cheap-as-free Air Scouts to support a Strategic Bomber attack; this effectively made air defence a waste of time.
An attempt to make the UEF T3 mobile sonar into something actually useful accidentally turned it into a ridiculously overpowered motor torpedo boat, requiring another patch to stop the ridiculous sight of flotillas of things which were technically buildings chasing battleships around.
Some of the Experimentals fall under this category. Also termed as "Game Enders".
Mavor: Can shoot anywhere on the map with extreme damage and exceptional accuracy. The shell can also pass through shields and destroy most buildings in one shot.
Scathis: A mobile artillery platform that rapidly fires low-yield nuke shells all over an enemy base. It has the range of Mavor but is terribly inaccurate.
Salvation: Rapidly shoots shells that break apart into 36 bomblets, causing widespread damage.
Paragon: Free resources out of thin air. Never run out of mass and energy again!
Yolona Oss: Fires a special Nuke that needs two Anti-Nukes to destroy. Given the fact that the special Nuke takes only one minute to build and is cheaper than a regular Nuke, the opponent will need eight Anti-Nuke stations just to protect against one Yolona Oss.
The expansion pack Forged Alliance allows players to construct experiments without having to wait until the final missions like the original game did. Very few of the missions have any real impetus to achieve objectives, thus many of the missions can if the player wants to, turtle in their base, constructing reams of tier 3 power generators and mass fabricators, until you have enough power and mass to construct game enders at which point you steam roll all of the map objectives in very quick time. The UEF are the best at this tactic, as they can build a couple of the Mavor artillery pieces within about 2 hours, and they will destroy every enemy building on the map in very short time, while still being able to build constant fatboy experimentals that the enemy have no hope of standing up to.
The scream that the Seraphim T3 bomber yells as it drops its payload can be quite terrifying
Offscreen Moment of Awesome: Forged Alliance had the introduction of an hostile alien race. So you'd expect to play missions where all three human factions try and defeat the alien race by themselves, realizing that they have to work together with their enemies, and working together to defeat it, right? Nope, all of that happens in a timeline cutscene.
Porting Disaster: Even though the new control scheme worked well enough, the X-box 360 simply couldn't handle the first game and it turned into a stuttering mess with frequent pauses and the occasional crash. The reduced graphics on the sequel prevent this.
Mission 4, Objective 3 of Forged Alliance. You never get a clue or a hint that your base is going to be attacked from all sides until you complete Objective 2 and see that you're surrounded and attacked by endless waves of T2 and T3 Seraphim Units, forcing you to start all over from the beginning if your base construction was very minimal AND you forgot to make a save beforehand.
Apparently, there was ONE clue, but so faint many missed it: During the opening briefing, there's a map of your LZ (landing zone) showing Dostya's position, yours and several other Seraphim positions surrounding you for several seconds. All in pretty much the EXACT same placement when Objective 3 happens... apparently the other objectives simply misled us.
And contrary to every other level in the campaign where a uef player can almost just build a marvor, sit back, and just tell it where to shoot to end the mission, on this level building a marvor will work against you as the cost will leave you vulnerable, and it cannot do anything to defend you.
They Changed It, Now It Sucks: The sequel did away with much of the economic complexity, added a research element while greatly reducing unit variety, and has significantly weaker graphics than the original or Forged Alliance. See Broken Base above.