I made it. I got to year 300 on my first try. I was a little worried for awhile because there was a space of about 60 years where alchemists were completely extinct in my nation, but I just fielded a few archer-heavy teams until I could recruit a new hero to take over the stronghold. Massive Chalice proved not to be as difficult as I initially feared.
As far as the story is concerned, I'm about to spoil the ending, so if you really want to experience Massive Chalice "pure" then you should stop reading now . . .
After waiting 300 years for the Chalice to charge up, it detonates, driving the Cadence out of the kingdom and breaking the enchantment that makes you immortal. Just before you fade out of existence, the voices inside the Chalice decide to tell you that your victory is only temporary, that the Cadence is fundamentally indestructible and that the last three centuries are all just part of a cosmic cycle . . . which seems like kind of a shitty thing to say to someone just before they die, even if you try to reassure them by telling them about the imminent golden age that will only fall after a few hundred years. On the other hand, this does explain why you get to replay the game from the very beginning, which is nicely in keeping with the game's insistence on making its basic gameplay mechanics part of its fictional world.
And that's it. There's no more story. A brief introduction and a brief ending, but only random events and random battles in between. That's the biggest problem with this game. It's trying to be a general activity, a repeatable fantasy strategy board game that's only loosely bound by plot. Unfortunately, the strategy isn't quite deep enough to support this and the story isn't strong enough to be a draw on its own. Overall, Massive Chalice is a decent game, but it's a shadow of the game it could be if its features were more fully developed.
From here, I think I'll go back and play iron man. I definitely won't finish the game again, but if I'm still alive six hours from now, I'll consider it a victory.