Good day! Thank you for leaving your feedback. The only instance where the game could possibly try to connect to the internet is right at the startup, when it tries to connect to Discord to set the Rich Presence status. The Discord Rich Presence integration is mentioned in the game's itch.io description.
As the game's programmer, it is my responsibility to fix this issue😅. Unfortunately, I was unable to replicate it. Blocking the game's incoming and outgoing connections in Windows firewall still allows it to run just fine on my Windows 10 machine.
Due to less than stellar programming on my end, there could be a slight delay between the game executable's launch, and the splashscreen appearing, as the game tries and fails to connect to Discord. Could it be that you're simply not giving the game enough time to launch?
I will investigate this issue further later today. If you could provide any additional information, I'd appreciate it very much.