I don't want to denigrate what Shine has done so far but if we're really honest.
We can break down the current state of work fairly easily..
Things you can easily do in Unity (via tutorials, templates, or asset store purchases):
- Over the shoulder camera system
- Gun combat
- Basic enemy attack AI
- Inventory system
What you can't do easily OOTB (must be manually created in scripting):
- Animation system
- Basic objectives system
- Camera motion event triggers (Sewer Door Puzzle)
- Attack Events (Sewer Zombie Waves)
Everything else art related (Not hard just time consuming):
- Terrain
- Models
- UI
- Animations
Having said all that.. a single talented developer could recreate what we currently have probably in 2 weeks time (dedicated). So at this point, there does seem to be zero forward progress being made, at least to those outside of the Patreon circle, no telling what updates he's posting internally.