Done with the game? Here are free mods! Download them and when you want to play add them to the list in the Modding tab in the launcher.
From the title screen you can access the level editor. You can use it to make your own levels or play levels made by others.
You can make more complex mods by replacing the game's own files with your own. Simply put your data in a 7z archive! You can replace the levels, the graphics, the sounds, etc.
Still not enough? No problem: if you can program, you can modify the game's source code and change even the most tiny details.