Alright, so I have some great feedback from you that I'm going to start actioning right now. Work has been really busy lately but hopefully, I can power through this in a few weekends.
1. Change the menus so that the player has to pick a difficulty to play on. Make this more clear so the player knows what they are doing and does not confound this with save slots.
2. Make the menus less ugly. I might have to dig up an asset pack for this.
3. Change how the autosave works. Consider a "saving game dialog".
4. Add a "Legend" to the upgrades screen that explains what each of the pickups does. This may have to be multiple pages and allow the player to flick through this.
Thank you so much for all of your feedback. And thank you for playing the game. I'll comment here once I fix all of these problems.