Logic behind allowing and disallowing Power Ups in DF Felltower

DF Felltower tries to play like an old-school, early-edition RPG game. It's heavily influenced by AD&D, Rolemaster, and my earlier-edition GURPS games. It is intended - like normal DF - to be a higher-powered version of the same. You sure don't start at "1st level" in DF.

But in any case, GURPS DF isn't quite like the source material. I end up disallowing a lot of potentially potent and/or useful adventures. No chi blasts, no magic bolts, no special kill shots, no special skill at parrying with your bow . . . not even if I wrote the damn ability up in the first place. I know cool, and I know the rules, but I also know DF Felltower isn't a kitchen sink game.

How do I decide?

- Is it basically mundane? If the ability is largely just a souped-up mundane ability . . . it's likely going in. I don't mind more power. I like more power. It allows me to put in more and more powerful foes.

- Is it wiz-bang and video gamey? It's likely staying out. If it allows you to bend reality to pull off some cool move . . . or bypass some core power limitation of the basic rules . . . it's out.

- Does it usurp another template? Does it let you replace another template's core skills? Thieves as combat coordinators, scouts as spellcasters, wizards as missile spell machine guns . . . not for DF Felltower.

- Is it a "must have"? Probably not allowed. If it's the kind of thing that, once allowed, isn't something a template can do without . . . I won't include it. I don't want a splatbook approach where a new power comes along and you must buy it or be permanently relegated to second class in your own field.

That's pretty much how I pick and choose.

And, importantly:

The default answer is no. It needs to be "Hell Yes!" or the answer is no. I don't need a Power Up to argue for exclusion, but for inclusion.