I know the humans fight back too early is a big problem down here in the comments but past that and with some strategy, this game becomes really fun. My only criticisms here are that some of the upgrades feel useless in midgame and later on, such as the reduce rocket damage by 50% upgrades being next to useless if you know how to spam scout and fighter ships midgame to mitigate damage to your mothership.
A better upgrade for midgame would've been to give armor points to ships to tank rocket (that would be too op though), or even better, SLOW down rocket speeds using some sort of gravity field or sabotage so that the player can take better advantage of the upgrade that gives you the ability to destroy rockets.
Oh and if you're trying to beat the game, it can be summed up in phases:
Scout phase: No rockets will be launched against you unless there are 5 scout ships in orbit, so use this time to build up mothership damage, and unlock the fighter asap. Otherwise if you have rockets firing at you, start replacing lost scouts immediately.
Fighter phase: It will be a long time until you reach the bomber phase, so stack up on ship damage and mothership damage again, you'll find yourself clicking earth alot here so its fine. Additionally, you don't have to have a full fleet of fighters at this point if you're broke, just keep racking up bones for upgrades until it is sustainable to max out fighters.
Bomber phase: Get the upgrade that lets you destroy rockets ASAP, and this midgame is essentially building up a fleet of bomber and defending them using the rocket interceptor upgrade to rack up bones. Piece of advise is to be economical about bombers, don't send them all out while you are incapable of intercepting rockets and be careful about replacing them immediately if lost. Longest phase of the game so far
Frigate phase: Its the same as the previous phase except the rockets are faster now and you have to learn to spam cheap ships to tank rockets for your frigates, this is shorter than the previous phase and introduces you to spam tactics. MAX OUT your ship damage and mothership damage before moving to the FINAL phase
Clicking the earth past this point for bones becomes irrelevant:
Cruiser phase: Earth starts an all out war and it ceases being a click-rockets-to-stop-them game to spam-ships-to-tank-them game. Just keep buying and maxing out your fleet of ships and buy every remaining upgrade in the shop. Its risky to try and attack/destroy rockets at this point because your fleet gets wiped out faster than you kill/destroy rockets, so its best to keep spamming fleets.
Overall, a very unique take on the clicking genre and its honestly really fun and kept me involved for minutes end.