I have decided to go for encrypting the save files. It might take a while till it's done because I have a really large update coming up. I will also try to find a solution for losing the old data, though I'm not sure it can be recovered to easily.
Important! I have been made aware of an important problem with the game's encryption. It doesn't affect much, only the score boards, since this is a single player game. To fix it, I will have to change some important code that will render all save files useless and everyone will have to start from scratch. Please tell me what you'd like me to do. Either leave it as it is, for everyone to play how they like it, or sacrifice the save files and make it fair for everyone.
First of all, thank you everyone who has commented and given me feedback! It helped me to improve the game very much; Changes in the updates tab. The good news is that I think I found what was causing the long white screen: the music. Apparently it's badly compressed and takes some time to load. If you wait a few seconds, it should be done, but slower computers might take longer. Bad news is that to fix the long load I have to remove it and/or reupload the game, which is likely to result in lost saves. Please tell me what you'd like me to do: leave it as it is, or sacrifice your saves.
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 "Heritage 2"){kind=icon}
To those who have white screen: everything should load quicker if you restart your browser and don't open too many tabs at once.