For download version pressing options closes the game, web version worked fine.
In web version one time the screen had a white overlay that never went away when I walked halfway through entrance room of the main area.
The main area, i feel, should be split into smaller areas so that it's more satisfying to clear, and also so you don't struggle trying to find any stray fujos you might have missed.
The main gun might be more fun if the bullets have a small amount of spread, starting at 0 spread when you pull the trigger and it slowly increasing. It would also help in killing fujos who aren't only in the direction you're facing, but not too much spread that you start to miss fujos too much.
If the main area isn't split consider adding indicators at the edge of the screens showing where remaining fujos are.
Sometimes they go towards the room entrances and it's hard to see them.