feat(sim): projectiles, items and inventory

game/sim/inventory.py

@@ -0,0 +1,31 @@
+class Inventory:
+    def __init__(self):
+        self.counts = {}
+        self.keys = 0
+
+    def add(self, kind, amount=1):
+        self.counts[kind] = self.counts.get(kind, 0) + amount
+        if kind == "key":
+            self.keys += amount
+        return self.counts[kind]
+
+    def count(self, kind):
+        return self.counts.get(kind, 0)
+
+    def has(self, kind, amount=1):
+        return self.count(kind) >= amount
+
+    def consume(self, kind, amount=1):
+        if self.count(kind) < amount:
+            return False
+        self.counts[kind] -= amount
+        if kind == "key":
+            self.keys -= amount
+        return True
+
+    def asDict(self):
+        return {"counts": dict(self.counts), "keys": self.keys}
+
+    def loadDict(self, record):
+        self.counts = dict(record.get("counts", {}))
+        self.keys = record.get("keys", 0)