Hi everyone! I'm the guy making Solar War and I always like to read what people are thinking about the game.
Here's some thoughts on the weapon and ship balance:
First off, yeah, lasers are supposed to be difficult to handle heat-wise. To some degree, the ship limits are set in such a way that it's hard to make maximum use of a ship with just a single weapon type (energy, projectile gun, missiles etc). For Destroyers, try mixing in mass drivers, proton beams or missile launchers to make the best use of your resources.
Later on, you have more options to juggle with for your heat management. Mixing in cold fusion power helps a lot with laser builds at that point, and keep in mind that you can have different types of reactors on a single ship. Currently, cold fusion doesn't come until TL8 (battlecruiser level), which might be a little late. I'll think about moving it down to the heavy cruiser level so you can play with more options earlier on.
On the topic of lasers, the upcoming version 0.31 will also see a new shield modification that doubles the shield effectiveness vs lasers but halves it against everything else. That should allow for some interesting choices.
As for missiles in the late game, they are supposed to vary in usefulness throughout the game, but maybe not this much. Once the AI gets its act together and starts gathering bigger fleets, flight time might become less of a factor simply because fights would last longer. I'd rather wait with any rebalancing there until I've optimized the AI a little more.
And indeed some weapons become available before you can reasonably build them into your ships. Most of those are because I simply haven't hooked them up to their proper point in the tech tree yet. There's also a few other modules that will still move to a later point in the tech tree, when I get around to it.
Old ship classes getting obsoleted: Kind of, sort of intended, at least in a main combatant role. I'm hoping that players can find some use for any old ship of Frigate and later class throughout most of the game: Frigates make cheap disposable point defense units, Destroyers can fill out your attack power somewhat (in part by grinding down enemy shields and point defenses by lots of small pinpricks), Light Cruisers have the biggest Warp capacity (this slowly goes down for each larger class).
Oh, and in the current Alpha, if you have driven the Aliens back to Eris, you can consider yourself as having won. At least until I add the real endgame or other sources of fun.
Anyway, I'm happy to see you talk about this as it helps me figure out where I might have to look into balancing. Thanks a lot!