Update 19
A bit more.
I made level 1-3, the last regular level in the upcoming demo. It introduces 2 new enemies (grunts with grenade launchers and heavies with cannons) and a new mechanic (explosive barrels), introducing more destructive mayhem to the game.
All I got left for now is a boss and 2 new weapons. I'm seeing a checkpoint not far away, and I'm expecting to get there in 3 updates or less.