Would it be possible to implement some new artifacts/skills that can be unlocked in Endless mode (and maybe have it tiered to unlock at some threshold explosion gold)? It could be a rare drop, which will be further compounded by the length of endless runs.
It's good there's some cross-building interaction (eg Pits boost all, Rockers boost Pan/Sluice) but if you look at all the bonus models, all (except the Pan) offers a x/n diminishing growth. Only the Pan can keep up with exponential cost. Looking forward to new shard skills (maybe can buy equipment slots, further reduce research time, etc), challenges, rare items [random stats maybe rather than fixed %].
Purely aesthetic, perhaps the ore can be 'decorated' with the different color gems to reflect an increasing GPS/GPC. Also hope that the stats page can show the 'underlying' stats separate from bonuses (eg, what is my base GPS, before the %multipliers) for the more hardcore min/max-ers out there.
Really looking forward to more content.