Added to the lair: 4/13/18
Genre: Strategy / Shooter / Vehicular Combat
Developer: Kodiak Interactive Software Studios
Wikipedia: Stratosphere: Conquest of the Skies
A war fought between a rock and a hard place
Stratosphere: Conquest of the Skies is a really obscure, really interesting game that, for whatever reason, completely slipped under the radar. It features an unusual combination of strategy and vehicular combat (kindof?) elements that make it quite unique, even today. Space Run, if you're at all familiar with that game, is one that bears a few similarities, but it's more akin to tower defense than this, since you're directly controlling/moving your ship here. There really aren't many, if any, games that I can point to and say it's similar to.
The basic idea is that you command and directly control a flying fortress - as in, a literal fortress, with buildings and cannons - atop floating rocks called "floatstone", which you maneuver and use to destroy opposing fortresses and installations.
You're able to design your fortress and make adjustments to it in real time, assuming you have the necessary resources; which can be gathered from resource points or by destroying enemy fortresses. Add new cannons or missile launchers, replace those thrusters with better ones, replace that wall with a force field, add on a mine launcher or spikes for ramming into enemy fortresses... there are a ton of different options for customizing your fortress the way you want.
You can play single scenarios or in a story-driven campaign. There's also a fortress builder/tester that I remember spending hours in as a kid, just trying out different combinations of things. I love this sort of thing and it's why I'm such a diehard Armored Core fan - giving me a bunch of tools for customization and just setting me loose is immensely appealing to me.
The game is, unfortunately, a little buggy even today. None of these are game-breaking, but they can be a little annoying. I have more info in the Special Notes section, but it's something you should be aware of.
Stratosphere is a really neat, unique, rarely talked about game that's worth a look.