I played the game awhile ago. Yes Leviathans had a lot of power, however solutions were 1)You didn't see them coming 2) You did not pay attention 3) you made the planet suitable for them 4) You had not seen them coming I am saying this for the most part because people complain about balance. But in the Beta I found a lot of units worked. I mean there were bugs, but the issues with balance perhaps was the t1 and t2 not so much on the fine tuned things. I think the units worked. I think you should add upgrades to the units. For example allow them to be OP say if you create a upgrade from a forge. Now the forge for that upgrade may take awhile perhaps longer than some nukes. But this isn't going to spam the game where the people who like it will be disappointed saving your company money and time which Uber does not have. Otherwise all units would have the SAME attack score the SAME armor rating and the game would be extremely boring. TW R2 did that and now Charriots are sooooo bad. They used to be accurate. I calculated they would ram with like 1 billion joules while a man was like 100? so 10,000 men would die. So please do not become TW2 where everyone thinks these are bugs and the communication between the community is so bad that people think the game's broken.
Upgrades would be a poor idea for the direction PA is headed and they are a confirmed no. Upgrades/research is one of the reasons why SupCom 2 flopped. Upgrades mean more micro. More focus on smaller groups of units. PA is supposed to be about. Plenty of games have had units all with the same attack and armor and they did just fine. SupCom 1 and FaF being good examples. Quite a few of the C&C games as well. Right now one of the major balance issues is with defensive structures. They're so cheap and effective that they pretty much invalidate basic units. PA is a moving target right now. It's far from being finished. Balance is being majorly tweaked all of the time.
*supcom2 I liked SupCom 2, but it shouldn't have had its label. It was fun, but it wasn't a ta inspired game, which is what its title implied. There have been several games which failed because of this, notably C&C4 and SimTown 2 (AKA Simcity Societies Atrocities).