Hello Dhenaro, thanks for playing our game!
For the upgrade shop it should been reserved for further stages where you can gain more gold and we should have been limit the upgrades for the demo.
Yes, we limit the game playtime so the player not stuck for too long on 1 run. We might implement survival mode if there's enough people demand for it .
For the itch we don't update it anymore since we do a major rewrite in the game code also implementing new features and things got broken, but in around 2 weeks time we will hand out a trial for the latest version on our Discord.
If you have anything to ask feel free to join our Discord server!