If you're going to let people be Toa, but not give them elemental powers or mask powers (which, for the record, is a step I approve of, hard to make things scary around a character who can set things on fire with their mind) then whats the point in letting them be Toa at all? They're just Matoran, but taller, so why not just stick to Matoran?
And if you really were dead set on species variety, why not just set it on Bara Magna? No-one there has any actual powers (pre Mata Nui anyway), its all within weapons. So just make sure they don't get any weapons (which, as an asylum, you should be doing anyway ) and you're golden. People could be Agori, Glatorian, Skrall...
Plus, there's bound to be horrific stuff left over from the Core War (case in point, the Baterra) which provides an easy origin for your monster
For once, I actually have a good answer to this question:
In the MU, Toa are the mightiest of the mighty. Sure, Makuta and some Dark Hunters are more powerful, but they're the exception, not the norm; further, Toa work in teams, which allows them combat such beings, when such a scenario arises. Thematically, the purpose of a Toa in such a setting is to cast a "mighty have fallen" vibe. In fact, it wouldn't be inappropriate to have Toa become the most discriminated against group, with Skakdi and the like taking advantage of the situation to pummel them while they can't do anything about it.
In fact, going off of my idea, that would actually make the situation; kill the ones who are unintentionally powering the facility, everything goes. One might also have the Monster catch wind of this, and start killing off Toa, hoping to cut off the power drained by the energy absorber and close off the facility; thus, rather than gain importance from their powers, they gain importance from their lack of powers.
It's all about how you set the tone, in this case. Of course, this really only works if players are willing to roleplay the situation appropriately. I fully endorse the Monster ganking those who don't.
"Up north, the undead are corraled into the undead asylum. To hollow and await the end of days."
Dark Souls is actually a primary inspiration for unnamed tank RPG.
Which will be done soon.
Hadn't really made the connection.
Get this thing done. Even if my main interest in a tank RPG is to see the number of Valkyra Chronicles references in the characters, it's still an interest.
*steals idea from Zehvor* if you're okay with my burglary, of course
Pssh, it's not burglary when it's given. I doubt I'll ever write an RPG again, so heck, all of my posts are open source.
-Toa Levacius Zehvor