What I'd fix:
- More visually standing out active and otherwise important objects, like ladders and such.
- Maybe make katana an off-hand weapon, like in DemonSteele?
- Speaking of gzdoom mods, check out Guncaster and Traliblazer. Lots of good ideas there.
- Katana and pistol feels unsatisfying. Maybe add windup to katana and reduce ROF for pistol(s), but make them oneshot things?
- Sometimes it's hard to figure where you are shot at from. Add the indication of damage direction.