I belive that will be changed in the future.. i think you could move any planet with enough of them.. even change their orbits which would be great to move closer then launch some nukes or arty unit cannons
Any robot advanced enough to build such engines would already know there is no point to building them on large planets or those with sufficient atmosphere to absorb the thrust forces.
That vote is invalid... There is no such thing as an "unmovable planet". Every planet can be moved if your are strapping enough engines on it. The number required scales with the cube of the diameter, but it's still possible to move every single one of them if you are just trying hard enough.
That's true but in game you can't really move all planets, besides the surface where you can put those halleys increases only with the square of the diameter, so there is a limit. Actually there isn't, you can move a planet with a gigantic radius with only one halley, but do you really want to wait that long?
That is the actual weird thing about the current implementation. You can't start to move the planet before all are in place. (And add more Halleys while already set in motion - if necessary.)
Just like the game prevents the player from building factories in invalid areas, it should prevent building a halley in invalid areas. I'd argue an immovable planet is an invalid area.
We've discussed the topic of 'unmovable planets' before in another thread. While it's true that theoretically any planet is moveable given enough force it does not sound like it will be implemented. This is what garat said regarding building boosters on any planet: And if this is the case, I would then agree that we should not be able to construct boosters on planets that we are not able to move. Here is that thread: https://forums.uberent.com/threads/planet-boosters.51353/
