The credits were always meant to be an OOC currency, while Lien is an IC currency.  The system of reward in proportion to mission difficulty was indeed pretty obvious.  I realize that I've made a problem by not properly defining 'ability upgrade', so I'll go ahead and do that now.  Somebody who gets an ability upgrade doesn't just receive new powers, if you thought that was what it was.  Rather, I view a semblance like a muscle; with training and use, it can be improved and used in new ways.  For instance, at the start of season two of RWBY the titular character uses her Speed semblance to create a jetstream that sucks in objects and carries them with her.  Our own characters can discover new ways to use their semblances.  For instance, Jack might find out that if he uses Midnight Lightening and crashed directly into an opponent, he can discharge all of his electricity at once, perhaps stunning the target.  Priscilla might find out that she can use her forcefields more accurately to create 'force armor' around herself or an ally.  These are the sort of things that might constitute an Ability upgrade.

Plus, since credits are OOC, we can use in-RP reasons to introduce upgrades we've bought.  For instance, after Diamond wins an A-level mission and Forsythe places first in a coffee-making contest, Forsythe can bu an ability upgrade and leave it in wait, and then suddenly in a particularly vicious fight IC with an Ogdoad, a wounded and frightened Diamond might, in a fit of anger, create a living monster out of her shadow to fight for her--and therein comes that upgrade.

By the way, if you're worried about people powering through missions and accumulating craptons of upgrades, listen up.  You can and will fail missions that you try that are too hard.  For this reason I was thinking of adding an 'Antagonist' category to missions, which allow one player to be the opposing force in that mission.  For instance, while team MODA might be the one to go on that convoy, it could very well be Sixsmith playing all the Grimm they encounter.  Let me know if you think this is a good idea.

Finally, concerning subplots.  What do you mean 'too limiting?'  Is it that there wouldn't be enough?  I could lower the pricing on them.  And the subplots I envision would be pretty specific actually.  For instance, if I hypothetically paid for a subplot, I could have us encounter Abel's long-lost brother, and repercussions would ensue.  Wouldn't effect the overall story too much; the only one majorly affected is my own character.


Also we're about to move on to fourth period IC.