Cool concept, the idea of having a 'countdown to ruin' before having to face a boss, and finding an optimal use of time to build your army, in real-time as well, kind of like a management simulator. The way the background changes, indicating the time of day, is my favorite detail of the project.
For a future iteration of this idea, it may be useful to see the way that different decisions affect the likelihood of beating the boss. In my run, I averaged around 90% likelihood each fight, but wasn't sure what components of my army composition contributed to this. Likelihood to beat the boss is probably the most important stat, so I'd recommend having that displayed in a big font somewhere in the main HUD, then you can see it update as you improve the army.
I was lucky in my rolls and beat all three bosses, but I could imagine it being very annoying if I lost to a 1/10 chance of defeat. I'd also recommend making some sort of target power level, and if you hit that, you win 100% of the time, and if you don't, you lose 100% of the time, to remove the variance. That's of course just my personal taste.
That's all, thanks for sharing!