I just grabbed this game here on sale on steam, and I am kinda surprised no body else has talked about this here. The goal stated by the designer is to simulate what space combat would be really be like.
http://store.steampowered.com/app/476530
The technology available is restricted to systems currently physically allowed, and a lot of math is used to simulate all the systems. You have to deal with waste heat, you need to protect your crew quarters from radiation, and orbital dynamics play a huge role in how an engagement turns out depending if you run past each other at 200km at 4km/s or you go for a zero/zero intercept with your opponent.
Similarly, your lasers are mostly invisible, only giving off a faint glow if you directly look at the emitter, and the plume of ablated material coming from the target. Kinetic rounds make up for it with tracer rounds in all colors of the rainbow smashing into your ships, and nukes light up the entire screen, but often manage to only heat up the skin of your ships.
For propulsion you have reaction drives, nuclear thermal rockets, magnetoplasmadynamics thrusters and resistojets, and your weapons are either kinetic (though there are chemical, railgun and coilgun variants), lasers and missiles, the latter can be nuclear tipped or with fragmentation warheads.
There is a neat campaign, and once you unlock module design the real game begins. Each of those modules has various parameters that can be adjusted, and you can design every module used in the game, including radiators missile launchers, crew quarters, fuses, fuel tanks...
Want multi GW lasers with 20m aperture? Nuke launching railguns? Kiloton heavy kinetic kill vehicles? Swarms of micromissiles? You got it. The modules can then be pieced together to build your ship of choice, which you then can unleash on your targets.
Overall it is a very neat but niche game. If you like tweaking a drive to get that last little bit of specific impulse out of a drive, you'll very much enjoy this. The dev (singular) is also still actively improving the game, and making it more and more accurate, various user suggested materials have been added to the base game for construction, the only downside is that many designs one tries to copy flat out don't work anymore because the game now knows the pumps would rip themselves apart and the laser cavity would be melted to slag.