In your game folder, in Mods directory, you will find text file named mods.txt. Open it. As it states: # Lines beginning with # are comment lines and thus ignored. # Each line here should either be the name of a mod .zip or the path to it. # The order in this .txt is the order in which the mods get loaded.
Of course you can configure mods by opening the game console (`), and AFAIR this way, you can disable/enable particular mods without exiting EtG. In your game folder, in Mods directory, you will find text file named mods.txt. Open it. As it states: # Lines beginning with # are comment lines and thus ignored.
When you open the console, or typing help will show you general commands using Mod The Gungeon, as well after opening the console, it will list mods which has been loaded. By typing particular "<mod name>", or "<mod name> help" will show you some commands/parameters to change and edit.
You can download a zip of the latest formal release from the Releases Page.
Casual – Intended for novice players; restricted song list, no failing, no LifeMeter, simplified UI, etc. You can read more about customizing what content appears in Casual Mode here.