ohh nice catch, I thought we'd removed that!
Originally you had to click the deck to spawn the next card, we decided that was kind of redundant and confusing for players. Looks like we never removed that onClick handler :D
Yeh, I've played it a bunch, and just rushing green and blue mines and discarding other cards seems a pretty valid strategy.
We've been coming up with ideas to expand the gameplay, along the lines of having add-on cards that you can add to other cards on your hand to give bonuses, maybe event cards that immediately do something like give/remove tokens.
I really like the idea of having some sort of one-off price for a card though, good idea!