It's certainly a game, I guess. You do things in order to prepare for a monster invasion and there are results from your actions but either it was not something I could wrap my head around, or I was vastly overthinking every piece, which honestly feels more likely.
In any case, I completed it and while I can't say for sure that I had fun I don't feel like I wasted my time. There's just not a lot of 'game' here to really critique.