Single handedly the best fan game ever made. I even prefer this to SOR4, which many consider to be the best of the series. It's a massive love letter to the original trilogy with branching paths to keep things fresh, and matches the pacing of my personal favorite (Bare Knuckle III). I do feel like v5.2 ruined the fun factor a bit, but fortunately 5.1 is still easy enough to find.