I guess the main issue with this is how you would manage to make each level (stage) different to the others, I imagine you have a plan on how you could make each opponent feel different from the last?
The rocks are the first opponent you fight. They're completely static, but it randomly shoots out rocks as it gets more damage.
Trees are a little more mobile. As they are about to get destroyed, they will sway back and forth, and fall right in front of it.
Fairies, humans, and youkai all have different abilities to trump your cards.
Also, how would you stop there from being a "perfect build", which would potentially be able to beat every single stage?
As said above, and below, your spell cards start off as something from an Easy Stage 1 Midboss: Easy to dodge, and quick to kill.
As your cards get used more and they improve, they'll eventually be something from an Extra stage boss.
Plus, fairies, humans, and youkai will have abilities that will potentially negate your spell card's affects. For example, Yukari teleports away from bullets when she's at the edge of the screen, Reimu has the smallest hitbox, Cirno can freeze bullets a la GFW, Seija will pull out a random item from ISC, etc.
So no spell card combo will reliably defeat everyone.
I guess you could stop that be making each area (or stage) have a specific amount of each type of spellcard (so one normal, 2 time outs and a multi-part, for example), but other then that I can't view how you would manage it
I'm trying to learn Unity so that I can make it in there, so there's that.
Anyway, You won't unlock survival cards until around your 4th spell card, when you have as much power as a stage 4-ish boss.
You also, as stated in my last post, that you are limited in terms of cards by how many Power and Point items you have.
You get more Power and Point items from completing scenes.
You've mentioned the idea of leveling spells, how would you manage to make this feel like it isn't grinding?
Same as ISC. Use the items (or spell cards in this case), and they get better. Like more bullets, the bullets move faster, the timer is set longer, etc.
Plus, these scenes may or may not be unreasonably hard, so the cards will just level up naturally as you rage through the scenes.
Wait.
I'm not the only one who wishes I could be the boss?
Yep.