-/* STASH map a state property value to a negative range, where the object cannot be
- * picked up but the value can be recovered later. Avoid colliding with -1,
- * which has its own meaning as STATE_NOTFOUND. */
-#define PROP_STASHED(obj) (STATE_NOTFOUND - game.objects[obj].prop)
-#define PROP_IS_STASHED(obj) (game.objects[obj].prop < STATE_NOTFOUND)
-#define PROP_IS_NOTFOUND(obj) (game.objects[obj].prop == STATE_NOTFOUND)
-/* Don't use this on an object wi nore thab 2 (unstashed) states */
-#define PROP_IS_FOUND(obj) (game.objects[obj].prop == STATE_FOUND)
-/* Magic number -2 allows a PROP_STASHED version of state 1 */
-#define PROP_IS_INVALID(val) (val < -2 || val > 1)
-#define PROP_IS_STASHED_OR_UNSEEN(obj) (game.objects[obj].prop < 0)
-#define PROP_SET_FOUND(obj) (game.objects[obj].prop = STATE_FOUND)
-#define PROP_SET_NOT_FOUND(obj) (game.objects[obj].prop = STATE_NOTFOUND)
+#ifndef FOUNDBOOL
+/* (ESR) It is fitting that translation of the original ADVENT should
+ * have left us a maze of twisty little conditionals that resists all
+ * understanding. Setting and use of what is now the per-object state
+ * member (which used to be an array of its own) is our mystery. This
+ * state tangles together information about whether the object is a
+ * treasure, whether the player has seen it yet, and its activation
+ * state.
+ *
+ * Things we think we know:
+ *
+ * STATE_NOTFOUND is only set on treasures. Non-treasures start the
+ * game in STATE_FOUND.
+ *
+ * PROP_STASHED is supposed to map a state property value to a
+ * negative range, where the object cannot be picked up but the value
+ * can be recovered later. Various objects get this property when
+ * the cave starts to close. Only seems to be significant for the bird
+ * and readable objects, notably the clam/oyster - but the code around
+ * those tests is difficult to read.
+ */
+#define PROP_STASHIFY(n) (-1 - (n))
+#define PROP_IS_STASHED(obj) (game.objects[obj].prop < STATE_NOTFOUND)
+#define PROP_IS_NOTFOUND(obj) (game.objects[obj].prop == STATE_NOTFOUND)
+#define PROP_IS_FOUND(obj) (game.objects[obj].prop == STATE_FOUND)
+#define PROP_IS_STASHED_OR_UNSEEN(obj) (game.objects[obj].prop < 0)
+#define PROP_SET_FOUND(obj) (game.objects[obj].prop = STATE_FOUND)
+#define PROP_SET_NOT_FOUND(obj) (game.objects[obj].prop = STATE_NOTFOUND)
+#define PROP_IS_NOTFOUND2(g, o) (g.objects[o].prop == STATE_NOTFOUND)
+#define PROP_IS_INVALID(val) (val < -MAX_STATE - 1 || val > MAX_STATE)
+#else
+/* (ESR) Only the boldest of adventurers will explore here. This
+ * alternate set of definitions for the macros above was an attempt to
+ * break out of the state encoding a per-object "found" member
+ * telling whether or not the player has seen the object.
+ *
+ * What's broken when you try to use thus is
+ * PROP_IS_STASHED_OR_UNSEEN. The symptom is game.tally getting
+ * decremented on non-treasures.
+ */
+#define PROP_STASHIFY(n) (-(n))
+#define PROP_IS_STASHED(obj) (game.objects[obj].prop < 0)
+#define PROP_IS_NOTFOUND(obj) (!game.objects[obj].found)
+#define PROP_IS_FOUND(obj) \
+ (game.objects[obj].found && game.objects[obj].prop == 0)
+#define PROP_IS_STASHED_OR_UNSEEN(obj) \
+ (!game.objects[obj].found || game.objects[obj].prop < 0)
+#define PROP_SET_FOUND(obj) \
+ do { \
+ game.objects[obj].found = true; \
+ game.objects[obj].prop = STATE_FOUND; \
+ } while (0)
+#define PROP_SET_NOT_FOUND(obj) game.objects[obj].found = false
+#define PROP_IS_NOTFOUND2(g, o) (!g.objects[o].found)
+#define PROP_IS_INVALID(val) (val < -MAX_STATE || val > MAX_STATE)
+#define PROP_SET_SEEN(obj) game.objects[object].found = true
+#endif
+#define PROP_STASHED(obj) PROP_STASHIFY(game.objects[obj].prop)