A thousand times this.
I agree that things like time travel, wormholes, teleportation, invisibility, and so on are actually technically possible. However, they all either require extremely advanced tech - invisibility requires nanotech, for example - or ludicrous power requirements. I am willing to fudge scales when it comes to gameplay mechanics - such as not making the player unable to carry 7800kg of steel - but not when it comes to mod internals.
That said, I could theoretically make a third mod, but that is a lot of work.
Answering the earlier question, somewhere in between. It does not have to actually be fully developed in the real world - tokamaks are not, either - but it does have to fully obey all the known laws of physics and not feel like something from Star Wars/Trek (whichever is the one with the planet laser).
How about a ground based high energy photon emitter for deorbiting space rocks to attain metals and minerals. You would need a trajectory computer to track the space rocks, and a lot of power to deorbit space rocks over time. It would not be a fast process, but the amount of power needed would be massive to deorbit anything with significant mass.
Maybe the photon emitter has to be placed at the build limit to simulate a geosyncronously orbiting sattellite powered by a microwave laser that the satellite hovers over to power said photon emitter. All of that obeys the laws of physics, and uses currently existent technology. More importantly, it uses lasers.