diff --git a/design.md b/design.md
index 401f4ac..fa6e96a 100644
--- a/design.md
+++ b/design.md
@@ -15,6 +15,8 @@
 The evil source is at about 50 km.
 The final goal is the evil source, so player is expected to mine about 50 km deep to beat the game.
 1 meter = one tile. 50 km = 50,000 tiles deep.
+There could be some post-endgame content from 50,000-60,000 blocks deep.
+Very unbreakable bottom or lava lake or whatever is at 60,000 blocks deep.
 
 ## Number of stuff
 
diff --git a/src/app.rs b/src/app.rs
index 260149e..940d280 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -57,7 +57,7 @@ impl App {
 
     fn do_update(&mut self) {
         let tp = self.game.camera_offset.tile_pos();
-        self.game.camera_offset.y += 33;
+        self.game.camera_offset.y += 800;
         imm_dbg!(tp);
         imm_dbg!(tp.to_chunk_and_local());
     }
diff --git a/src/math.rs b/src/math.rs
index 8f581c8..8a131e1 100644
--- a/src/math.rs
+++ b/src/math.rs
@@ -18,9 +18,10 @@ impl WorldPos {
         }
     }
     /// Horizontal center of the world
-    pub const CENTER: WorldPosScalar = WorldPosScalar::MAX / 2;
-    /// Vertical surface level
-    pub const SURFACE: WorldPosScalar = WorldPosScalar::MAX / 16;
+    pub const CENTER: WorldPosScalar =
+        (TilePosScalar::MAX / 2) as WorldPosScalar * TILE_SIZE as WorldPosScalar;
+    /// Vertical surface level. You can build 5,000 blocks upwards
+    pub const SURFACE: WorldPosScalar = 5000 * TILE_SIZE as WorldPosScalar;
     pub const SURFACE_CENTER: Self = Self {
         x: Self::CENTER,
         y: Self::SURFACE,
@@ -28,7 +29,7 @@ impl WorldPos {
 }
 
 pub fn wp_to_tp(wp: WorldPosScalar) -> TilePosScalar {
-    wp / TILE_SIZE as TilePosScalar
+    (wp / TILE_SIZE as WorldPosScalar) as TilePosScalar
 }
 
 #[test]
diff --git a/src/world.rs b/src/world.rs
index 7387f55..72a1eb6 100644
--- a/src/world.rs
+++ b/src/world.rs
@@ -1,7 +1,7 @@
 use fnv::FnvHashMap;
 use rand::{thread_rng, Rng};
 
-type ChunkPosScalar = u32;
+type ChunkPosScalar = u16;
 
 #[derive(Hash, PartialEq, Eq, Debug, Clone, Copy)]
 pub struct ChunkPos {
@@ -95,7 +95,7 @@ fn test_to_chunk_and_local() {
 }
 
 // Need to support at least 4 million tiles long
-pub type TilePosScalar = u32;
+pub type TilePosScalar = u16;
 
 const CHUNK_EXTENT: u16 = 128;
 const CHUNK_N_TILES: usize = CHUNK_EXTENT as usize * CHUNK_EXTENT as usize;