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.
Crowning Music of Awesome: The music has been specially composed for the game, giving each side its own specific type of music. Eurasian Dynasty has pompous, militaristic classic music fitting its blunt, crude aspect; Lunar Corp eerie, spacey sounds akin their space hippie-ness; United Civilised States hard rock fitting their industrialized nation. The Moon Project takes this already awesome music, and adds an overproduced futuristic feel to it. Then there's the three sides' promo clips, where the UCS clip is structured more like a music clip (with Nukes) than a propaganda clip.
The sequel, Earth 2160, comes bundled with a soundtrack CD, and given the nice selection of atmospheric tunes, you can't really blame them.
Game Breaker: UCS plasma cannons, hands down. Insane damage, very high rate of fire AND infinite ammo.
And The Moon Project adds Anti-aircraft plasma cannons making plasma weaponry even more overpowered.
Until long range artillery level the towers.
Also, aircraft in 2150's campaign, due to the AI's love of anti-ground only energy weapons.
Les Yay: Played for Laughs; during one Mission Briefing of the Neo Campaign in the original game (playing LC and deciding to join with the ED) Neo mentions that in the case of Fang's superior not going with his methods, he will release videos of her making out with the girl from the progress department. She is understandably very angry about that.
ED forcibly turns soldiers into cyborgs to pilot their vehicles.
The UCS is not better. They use cyberized human brains to pilot their mechs and aircraft.
Sequel Displacement: Few people have heard of Earth 2140, which started the series, and was a fairly decent game in its own right, if not as spectacular or out of the ordinary as its sequels.
That One Level: All of the first five or so ED missions tend to be unreasonably hard by virtue of the enemy sending highly-upgraded units at you just minutes into the missions. The worst is the semi-hidden Alaska mission where the player has to find a Soviet underground base (not very difficult), then has to mine 50,000 credits (doable) while being attacked by three UCS enemies spamming missile bots before the player is even allowed to construct anything (stupid).