How do I use Halleys?

You can't yet.

I have figured out that 100-200 radius needs 3 thrusters 200-300 needs 25. I have seen 5 but I have no idea how to make such a planetoid.

I concur. Might have something to do with the mass, maybe?

So I managed to get the number of Halleys on a small planetoid I needed, engaged it and then waited for 35 minutes and it was still circling around the star. Does it usually take so long before it closes in on the target and crashes?

How bout some engines floating in space.

There needs to be a little balance tweaking with the number of Halleys needed to move a planet.
Only 3 Halleys needed for a radius 200 moon and 25 for a radius over 250

THIS NEVER WORKS FOR ME.

So frustrating after playing a full game and about to wipe out a planet. Every single time i just click engage, then click target and the word engage just stays in red and nothing happens. No option to start annihilation/.

Have you actually zoomed into the planet you wanna hit and then clicked a point on the surface? If you're in the system view it won't work just clicking a planet. Oh and you need to click engage after you click your point on the surface. Hope that helps.

This does not work for me either. When I look into the top right corner I can only select planets, but there are no icons indicating the number of halleys I need or have. There is no button with which I could activate the halleys. Please help.

I know this is not a thread about teleporters, but if you could tell me how to link two teleporters than I would be very grateful.

No icons means that that planet cannot be moved. You can make your own system in the system editor. When you create a planet, you can indicate the number of Halleys needed for moving that planet. Once you have a system that does have movable planets, look at this tutorial by brianpurrkiss on how do it. The tutorial is about moving a planet, rather than smashing it into another planet, but it's almost the same and mentioned in the video.

You can link teleporters by selecting the first teleporter, then move the camera to the second teleporter. Your icon should turn into two yellow/orange arrow thingies. Right clicking the second teleporter links them together. And another tutorial.

Thanks very much.