Corvettes....

They are very good against everything with their "Composite" damage type plus being cheap and quick to produce.

Use flak frigates to fight them.

Corvettes reach "critical mass" (an expression that means the point at which the first pass or "alpha strike" is lethal to low-level capitals) very easily and use the Composite damageType which is shared with the Heavy Cruiser and has damage bonuses to most armor types.  They are cheap and can be built within seconds.  As such, people can build them very easily en masse and reach critical mass with them.  Mass Corvettes are good for the same reason mass Bombers are: high damage and easy critical mass, though bombers are late-game and corvettes are early-game.

The best counters to them are capital/titan AoE abilities and flak.  Flak will shred them easily.  I've also read that LF will win when outnumbered 2 to 1.  That said, the alpha or beta strike when massed will probably kill your capitals, rendering your fleet much more susceptible to the abilities of their capitals.

Corvettes also have excellent speed...players can amass a swarm of them and have them just jump jump jump from planet to planet, razing structures and extractors....you can't catch them, even with flak, and PJI's aren't going to do you much good...too hard to get that early in the game, and corvettes will just destroy them anyway...

Corvettes also have excellent speed...players can amass a swarm of them and have them just jump jump jump from planet to planet, razing structures and extractors....you can't catch them, even with flak, and PJI's aren't going to do you much good...too hard to get that early in the game, and corvettes will just destroy them anyway...

And this is the part where you use your fleet to attack his planets. Either he pulls his corvettes back, or he gets to destroy some petty extractors and research labs.

You wipe out one world while he's wiping out all of yours.  That definitely sounds like a fair trade.. 

Looks good on paper, doesn't work out on practice...whoever strikes first wins because corvettes can wipe out factories very quickly...

Even if that weren't the case, corvette raids are often used when a player is double teamed...one enemy raids with corvettes while the other attacks with a more conventional force...makes suicide spot a lot more difficult to manage even if you are more skilled...

Biggest problem with corvettes is their speed...flak only are useful in large numbers and when you force a pitched battle...but doing so is easier said than done...

I think corvettes have reached a good balance point and don't need to be changed much from here. They are indeed "the" unit at the beginning of the game but people who know how to play the game don't get overrun by them. You just have to start every game thinking "I am going to get attacked by a swarm of corvettes." Then you are fine. You have options: build your own corvette fleet, start a flak defense, go for a starbase, or [imagine this] scout your opponent to see what he's up to you and prepare your defense.

By mid-game, these units are fairly worthless if your opponent is up to snuff. The only good thing is to keep about 10 of them on-line so that you can zap the enemy's construction frigates quickly when you pop into a system with your fleet.

Flak are too expensive and slow to effectively force direct confrontation with corvettes early to actually stop corvettes from running free.

I think Mecha-Lenin will beg to differ...some might say he "knows how to play the game"....it is not a question of skill or simply "knowing" how to counter them...they are the early game and if you are even slightly outnumbered there is virtually no hope...

SB defences will not do you any good against corvette raiding...even if the corvettes can't take on your SB, they'll simply move on to another gravity well and raid there...the resources you plop down to maybe protect one planet will cripple your offensive ability and allow you to get completely walked over by more conventional forces later...

Scouting your opponent does little in regards to corvettes...even if you know where and when your enemy is hitting you with these things, you still aren't going to be able to effectively counter them...flak can't catch them, and can't even kill them fast enough unless you have a ton of flak...

That corvettes is marginalized late game is a moot issue...early game they are the dominant unit and they make 2v1s impossible situations for the suicide player....