The D&D version of this usually turns ugly fast, but isn't on the list of banned topics.

As long as this thread stays on GURPS - and remains civil - it can remain.

Aah! Good to know! Thanks!

I have the potential for psionics and chi powers in my GURPS game. I don't mind it. Don't see why anyone should.

I like to start off psi either a) in a world that knows about it (yes, so mind shields are available), b) weak enough that you can't just casually mind-control the first ten people to cross your path, or c) so costly to use that you're not going to just be using it casually.
Or d) you answer to a higher authority, who will take a dim view of excess usage, or e) everyone has psi at some level.

There are many ways to make sure it doesn't go out of control.

What I do like is the Psionic Powers book, which gives psi its own distinct flavour; on the one hand, you have to roll for previously "you got it, you use it" advantages, but on the other hand, you can get more bang for your buck if you roll well. Swings and roundabouts, swings and roundabouts.

One of the major problems many GMs have had with powerful psi in a game is the 'invisible hammer' syndrome; psi, by its nature, is invisible to use, and can be utilised to take down people who have no idea who is attacking them, as opposed to the standard super-power, which is highly traceable.

The simplest thing, of course, is to accept that psi will be active in your game and make plans to accommodate it. Incorporate it as a factor. Make one of your villains someone who absorbs psi power, to the detriment of the psi in question. Give them an adventure where they go up against a bunch of highly trained rogue government psis ... or a bunch of back-alley psis, long on talent but short on formal training, who have banded together for mutual protection.

There are many ways and means, and not all of them involve banning psionics or even nerfing it.

GURPS Powers is suppose to be the answer to your psionics questions.

My game is Psi friendly, but most players went with magic. Go figure.

When I think of Psionics in Fantasy games I immediately think of Elf Quest (anyone who hasn't read these absolutely should).

Which is the way I would like it. Psionics more rare than Magic.

Absolutely loved Elfquest