I like this a lot.
It seems braindead at first but there's actually a good bit of strategy with swapping characters and causing dice to overflow/underflow.
Classic mode suffers by only having one character(at least in the bit i played maybe you get more later). Game should be balanced around a party as that's where the fun is.
There's a lot of potential when it comes to adding new mechanics. (stuff like elemental dice/status effects,)
Some small things to point out tho:
>When there's dialog i should be able to click anywhere to skip it rather than the go button
>Similar thing with disabling spells, i don't want to have to click the bubble again to exit cast mode, maybe make right click disable it.
>no full screen
>+1 on not knowing what the crystals are I'm presuming they will become useful with more content.
>i think the crt effect is a little bit much. consider adding a slider that changes the intensity.
I'm looking forward seeing this fleshed out more, this is an excellent base.