The engine is way to costly to build as it is right now, one can't afford over 100K to build the thing. though if your looking for ideas for the gun itself, it was a wave motion accelerator,super energized Photon particle beam technology.

For the engine, it's normal that it's this costly as it's still a Work-In-Progress and not meant to be used yet. Once I am done fully creating it, then I will obviously reduce its cost and make it viable to research and install.

I found that out after I posted that. I loved the old star blazers show, when the theme music started you were sure that the evil forces were in for it,lols. If you would like to discuss weapon ideas, feel free to send me a friend request. I used to love design advanced weaponry for gaming.

Planned upcoming major feature:
DEFCON Policy. This will act as a set of modifiers and the way to "restrict" higher tier technology at least until battleships themselves can find themselves officially limited by "Space UN regulations".
This feature and a couple extra minor balance changes are gonna come in 1.1.0 of the mod.

EDIT: That moment when you imagine all that a specific change will bring and can already imagine 3-4 issues that will pop up from the ship designer if you implement a specific mechanic....
Pre-emptively known issues for this change:
1. the ship designer doesn't understand you're telling it to "disable" a specific design when you drop the DEFCON level later on
2. it understands and removes the "advanced weaponry"... but then forgets to auto-complete the design.
3. if the AI goes and fix the design, the game will accidentally warn you that ships need refitting, which you may not want (unless I manage to put most of the maluses on the weapons themselves...)