The theme is very well integrated in the game! It really is inevitable doom. However, it doesn't feel frustrating when you lose due to all the upgrades and defenses you can buy afterwards. I do wish you could upgrade the defense units or weapons you buy. It would give more for the player to work towards late game. But I understand this is a game jam submission and thus should not be a grind to experience. A solid game loop and a solid game. Great job!