It is not possible to save manually, but the game automatically saves at different times :

• at the launch of a new loop
• at the beginning of a battle
• when you enter the camp
• when you build a building in the camp
• when you start an expedition
• after dialogues
• after achieving an achievement

Please note that you can only have one save with the free version of Loop Hero. With the complete version, you will be able to have 3 different save slots!