Where are the game save checkpoints?

[AetherGamer]

How do I know when I've reached a checkpoint and can exit the game, knowing that my progress is saved up to that point?

[Kiris_Ditex]

I wondered the same thing. When I finished the intro (achievement popped) and I was sent to the next level. I quit and on the main menu it showed "Resume at (whatever the 2nd level was) so I assume that it saves at the end of each level. I didn't test it in between starting the first level and finishing it.

[Apprendista]

This is a problem