Now now...my turn to add my piece of advice (constructive of course...as I love helping and expect people to do the same for me).
1) Ships not powerful enough.
This is my first point as I have noticed that well we are sort of limited on the ships that we can buy throughout the game. (research in fleet supply being our only "upgrade source"). At the start with their elevated cost and the relative lack of ressources, its actually extremely slow to build any decent sized fleet, let alone permanently maintain it!
Its real nice having a 15 autocannon vessel to start..but vs barely 4-5 ship planets..hes out in no time! And with his high cost..thats something that hurts big time!
1.1) Speaking of research, you should have ONE RESEARCH TAB! Plundering...in which you would have handfulls of researches designed to upgrade the plunder ability into something truly marvelous and utterly powerful! Cus lets face it...relying on plunderers which get killed in 10 secs as a source of income will not cut it to sustain the fleet in prolonged battles!
As such, I propose you give the plunder ability a BIG BIG BIG BIG BIG..did I foget to mention BIG boost! Cus only 30 ressources per ship is far from enough! At start yes..but not in the long run!
1.2) Which leads me to another idea! Like you say..Pirates = Plunder! Which means either EVERY SHIP NEEDS PLUNDERING ABILITIES! Calibrate for each (ie. 10 ressources if missilor is in range, 20 if executor is in range...200!!! if PLUNDERER is in range (then it would be worth it to make that ship)) OR make a FREE EXTREME PLUNDERER! which would be the money maker of the fleet and would "create money"during and IN-BETWEEN BATTLES!!!
'cus lets face it..this is no Parako Probe, you dont cloak and "suck" a percentage of income from planets...You need vessels and battles to survive so if once the map is cleared and your ennemy is just turtling in his corner building a massive fleet!
You arent getting ANY cash! plus since you cant colonise...hell take ALL planets except for yours and then...well I'll let you guess what happens!
2) No Planetretakingstopper vessel (yeah people its well written )
This leads me to my next major point, the No Planetretakingstopper vessel !!! now this is A NECESSITY FOR YOU (and me for that matter)!!!! What I mean is you cloear planets and then cannot colonise. As such, opponent can just barely send a colony vessel after you and basta...all youre hard work just gave him a free planet! That x30 planets in a normal game...and you spared him a LOT of wasted credits and a clear shot at upgrades!
Therefore, you need to build a "Turtle Ship" (I say you do..but its of course..only an idea), which would settle in a neutral grav well and prevent any attempt to colonise UNLESS it is destroyed (sort of like my Homeworld but a mobile version of it)! That way you protect your back as you plunge into ennemy territory!
3) Too slow of a start!
The start is deadly slow! Sorry to say but with starter cash, I managed to upgrade my planet once and buy 3 of the 15 autocannon ships (basic attack craft I gather) and well...didnt go far with that . So I would propose either reducing ships cost or allowing the pirate player a large bonus starter lot of cash in order to expand rather quickly at start! As of the moment, the Pirates are extremely vulnerable to rushes.
Hope Im not killing you under all that! But since you helped me..I wanted to be as precise as possible to show my gratitude !
If you have any issues...Im just a PM away