Yes, i played and loved the Kingdom games :)
I can see how there is a similarity especially in the waves, although i didn't conciously think about that when designing the mechanics. But of course i'm influence by all the games i played
I love the music of Kingdom, so i also gave that as a reference to Cameron (who made the music for dome romantik). I think it's similar too, which i like a lot. I listened to the Kingdom OST thousands of times while working on games.
There aren't different endings yet, and we haven't planned on any for this version. However, we are working on a ton of things for the full version, demo coming soon. Community playtest starting this weekend over our discord, please join if you like :)