diff --git a/kiln-core/src/glyph.rs b/kiln-core/src/glyph.rs
index f91d7c3..7a75a88 100644
--- a/kiln-core/src/glyph.rs
+++ b/kiln-core/src/glyph.rs
@@ -116,6 +116,10 @@ impl Glyph {
     pub const fn is_visible(&self) -> bool {
         self.tile != '\0'
     }
+
+    pub fn is_transparent(&self) -> bool {
+        self == &Self::transparent()
+    }
 }
 
 /// The `tile` value for a glyph that draws nothing — the `serde` default, used
diff --git a/kiln-core/src/tile.rs b/kiln-core/src/tile.rs
index 5e2744f..5fc33e6 100644
--- a/kiln-core/src/tile.rs
+++ b/kiln-core/src/tile.rs
@@ -215,6 +215,7 @@ pub struct SensorSpec {
     pub y: usize,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub script: Option<String>,
+    #[serde(default, skip_serializing_if = "Glyph::is_transparent")]
     pub glyph: Glyph,
     #[serde(flatten, default)]
     pub optics: Optics,
diff --git a/maps/dark.toml b/maps/dark.toml
index 3748593..aff6bd4 100644
--- a/maps/dark.toml
+++ b/maps/dark.toml
@@ -12,7 +12,7 @@ hidden = """
 fn tick(me, dt) {
     if !me.waiting {
         say("Who's there?");
-        delay(2);
+        delay(2.0);
     }
 }
 """
@@ -27,19 +27,18 @@ fn bump(me, _dir) {
 }
 """
 
-[boards.cave.map]
+[boards.cave]
 name = "The Cave"
 width = 40
 height = 15
 dark = true
-floor = { generator = "stone" }
+floor = { biome = "stone" }
 
 # The 'H' object glows magenta inside a walled chamber: its light fills that room
 # but the player can't see in until they line up with the gap in the wall. 'L' is
 # an amber lantern out in the open, and 'T' is a wall torch (glowing terrain) off
 # in a far corner — a warm point of light you'll only reach by walking to it.
-[boards.cave.grid]
-content = """
+grid = """
 ########################################
 #                                      #
 #                                      #
@@ -56,9 +55,39 @@ content = """
 #                                      #
 ########################################
 """
-[boards.cave.grid.palette]
-"#" = { kind = "wall", tile = "#", fg = "#808080", bg = "#404040" }
-"@" = { kind = "player" }
-"T" = { kind = "torch" }  # glowing terrain: emits its own warm light
-"H" = { kind = "object", tile = 2, fg = "#cc66cc", bg = "#000000", solid = true, light = 5, name = "hidden", script_name = "hidden" }
-"L" = { kind = "object", tile = 15, fg = "#ffcc55", bg = "#000000", solid = true, light = 6, name = "lantern", script_name = "lantern" }
+[boards.cave.palette]
+"#" = { type = "builtin", kind = "wall" }
+"@" = { type = "player" }
+
+# A wall torch. There is no `torch` builtin — a light source is just an object
+# with a `glow` radius and no script.
+[boards.cave.palette.T]
+type = "object"
+enter = "block"
+glow = 4
+tile = "*"
+fg = "#ffaa33"
+bg = "#000000"
+
+# Glows magenta inside the walled chamber: its light fills that room, but the
+# player cannot see in until they line up with the gap in the south wall.
+[boards.cave.palette.H]
+type = "object"
+script = "hidden"
+name = "hidden"
+enter = "block"
+glow = 5
+tile = "☻"       # CP437 2 — `tile = 2` is equivalent
+fg = "#cc66cc"
+bg = "#000000"
+
+# An amber lantern out in the open, near the player.
+[boards.cave.palette.L]
+type = "object"
+script = "lantern"
+name = "lantern"
+enter = "block"
+glow = 6
+tile = "☼"       # CP437 15
+fg = "#ffcc55"
+bg = "#000000"
diff --git a/maps/tiny.toml b/maps/tiny.toml
index 8faa0cb..9215bab 100644
--- a/maps/tiny.toml
+++ b/maps/tiny.toml
@@ -37,7 +37,7 @@ grid = """
 """
 [boards.start.palette]
 "#" = { type = "builtin", kind = "wall" }
-"o" = { type = "builtin", kind = "crate", glyph = { tile = 254, fg = "#aaaaaa", bg = "#000000" } }
+"o" = { type = "builtin", kind = "crate", tile = 254, fg = "#4444bb", bg = "#000000" }
 "@" = { type = "player" }
 # "G" = { type = "object", tile = 35, fg = "#aa3333", bg = "#000000", enter = "block", script_name = "greeter" }
 "h" = { type = "builtin", kind = "heart" }