diff --git a/src/pg_rad/simulator/__init__.py b/src/pg_rad/simulator/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/pg_rad/simulator/engine.py b/src/pg_rad/simulator/engine.py
new file mode 100644
index 0000000..8de7e98
--- /dev/null
+++ b/src/pg_rad/simulator/engine.py
@@ -0,0 +1,63 @@
+from typing import List
+
+from pg_rad.landscape.landscape import Landscape
+from pg_rad.simulator.outputs import (
+    CountRateOutput,
+    SimulationOutput,
+    SourceOutput
+)
+from pg_rad.physics.fluence import calculate_fluence_along_path
+from pg_rad.utils.projection import minimal_distance_to_path
+from pg_rad.inputparser.specs import RuntimeSpec, SimulationOptionsSpec
+
+
+class SimulationEngine:
+    """Takes a fully built landscape and produces results."""
+    def __init__(
+        self,
+        landscape: Landscape,
+        runtime_spec=RuntimeSpec,
+        sim_spec=SimulationOptionsSpec
+    ):
+
+        self.landscape = landscape
+        self.runtime_spec = runtime_spec
+        self.sim_spec = sim_spec
+
+    def simulate(self) -> SimulationOutput:
+        """Compute everything and return structured output."""
+
+        count_rate_results = self._calculate_count_rate_along_path()
+        source_results = self._calculate_point_source_distance_to_path()
+
+        return SimulationOutput(
+            name=self.landscape.name,
+            count_rate=count_rate_results,
+            sources=source_results
+        )
+
+    def _calculate_count_rate_along_path(self) -> CountRateOutput:
+        arc_length, phi = calculate_fluence_along_path(self.landscape)
+        return CountRateOutput(arc_length, phi)
+
+    def _calculate_point_source_distance_to_path(self) -> List[SourceOutput]:
+
+        path = self.landscape.path
+        source_output = []
+        for s in self.landscape.point_sources:
+            dist_to_path = minimal_distance_to_path(
+                path.x_list,
+                path.y_list,
+                path.z,
+                s.pos)
+
+            source_output.append(
+                SourceOutput(
+                    s.name,
+                    s.isotope.name,
+                    s.activity,
+                    s.pos,
+                    dist_to_path)
+            )
+
+        return source_output
diff --git a/src/pg_rad/simulator/outputs.py b/src/pg_rad/simulator/outputs.py
new file mode 100644
index 0000000..395317f
--- /dev/null
+++ b/src/pg_rad/simulator/outputs.py
@@ -0,0 +1,25 @@
+from typing import List, Tuple
+
+from dataclasses import dataclass
+
+
+@dataclass
+class CountRateOutput:
+    arc_length: List[float]
+    count_rate: List[float]
+
+
+@dataclass
+class SourceOutput:
+    name: str
+    isotope: str
+    activity: float
+    position: Tuple[float, float, float]
+    dist_from_path: float
+
+
+@dataclass
+class SimulationOutput:
+    name: str
+    count_rate: CountRateOutput
+    sources: List[SourceOutput]