diff --git a/code/apps/server/header/blocks.h b/code/apps/server/header/blocks.h
index c9b7730..5fe3c3e 100644
--- a/code/apps/server/header/blocks.h
+++ b/code/apps/server/header/blocks.h
@@ -16,3 +16,5 @@ char *blocks_get_name(uint8_t id);
 uint8_t blocks_get_tex_id(uint8_t id);
 char blocks_get_symbol(uint8_t id);
 uint32_t blocks_get_flags(uint8_t id);
+uint32_t blocks_get_biome(uint8_t id);
+uint32_t blocks_get_kind(uint8_t id);
diff --git a/code/apps/server/header/blocks_info.h b/code/apps/server/header/blocks_info.h
index 547b70c..de479c1 100644
--- a/code/apps/server/header/blocks_info.h
+++ b/code/apps/server/header/blocks_info.h
@@ -5,6 +5,7 @@ typedef enum {
     BLOCK_KIND_GROUND,
     BLOCK_KIND_WATER,
     BLOCK_KIND_WALL,
+    BLOCK_KIND_HILL,
     BLOCK_KIND_HOLE,
 } block_kind;
 
diff --git a/code/apps/server/source/blocks.c b/code/apps/server/source/blocks.c
index 221abaa..625623b 100644
--- a/code/apps/server/source/blocks.c
+++ b/code/apps/server/source/blocks.c
@@ -40,3 +40,11 @@ char blocks_get_symbol(uint8_t id) {
 uint32_t blocks_get_flags(uint8_t id) {
     return blocks[id].flags;
 }
+
+uint32_t blocks_get_biome(uint8_t id) {
+    return blocks[id].biome;
+}
+
+uint32_t blocks_get_kind(uint8_t id) {
+    return blocks[id].kind;
+}
diff --git a/code/apps/server/source/blocks_list.c b/code/apps/server/source/blocks_list.c
index 47c0731..45d93c3 100644
--- a/code/apps/server/source/blocks_list.c
+++ b/code/apps/server/source/blocks_list.c
@@ -4,5 +4,6 @@
 static block blocks[] = {
     {.tex_id = ATLAS_XY(0, 0), .name = "base-ground", .flags = 0, .kind = BLOCK_KIND_GROUND, .biome = 0, .symbol = '.'},
     {.tex_id = ATLAS_XY(1, 0), .name = "base-wall", .flags = BLOCK_FLAG_COLLISION, .kind = BLOCK_KIND_WALL, .biome = 0, .symbol = '#'},
+    {.tex_id = ATLAS_XY(2, 0), .name = "base-hill", .flags = BLOCK_FLAG_COLLISION, .kind = BLOCK_KIND_HILL, .biome = 0, .symbol = '^'},
     {.tex_id = ATLAS_XY(0, 1), .name = "base-water", .flags = BLOCK_FLAG_COLLISION, .kind = BLOCK_KIND_WATER, .biome = 0, .symbol = '~'},
 };
diff --git a/code/apps/server/source/world_gen.c b/code/apps/server/source/world_gen.c
index 2747476..da910c7 100644
--- a/code/apps/server/source/world_gen.c
+++ b/code/apps/server/source/world_gen.c
@@ -4,19 +4,45 @@
 
 #include <math.h>
 
-static void world_fill_rect(uint32_t id, uint32_t x, uint32_t y, uint32_t w, uint32_t h) {
+#define WORLD_BLOCK_OBSERVER(name) uint32_t name(uint32_t id, uint32_t block_idx)
+typedef WORLD_BLOCK_OBSERVER(world_block_observer_proc);
+
+static void world_fill_rect(uint32_t id, uint32_t x, uint32_t y, uint32_t w, uint32_t h, world_block_observer_proc *proc) {
     for (uint32_t cy=y; cy<y+h; cy++) {
         for (uint32_t cx=x; cx<x+w; cx++) {
+            if (cx < 0 || cx >= world_width) continue;
+            if (cy < 0 || cy >= world_height) continue;
             uint32_t i = (cy*world_width) + cx;
+
+            if (proc) {
+                uint32_t new_id = (*proc)(id, i);
+                id = (new_id != BLOCK_INVALID) ? new_id : id;
+            }
+
             world[i] = id;
         }
     }
 }
 
-static void world_fill_dot(uint32_t id, uint32_t x, uint32_t y, uint32_t w, uint32_t h) {
-    uint32_t w2 = (uint32_t)floor(w/2.0);
-    uint32_t h2 = (uint32_t)floor(h/2.0);
-    world_fill_rect(id, x-w2, y-h2, w, h);
+static void world_fill_rect_anchor(uint32_t id, uint32_t x, uint32_t y, uint32_t w, uint32_t h, float ax, float ay, world_block_observer_proc *proc) {
+    uint32_t w2 = (uint32_t)floorf(w*ax);
+    uint32_t h2 = (uint32_t)floorf(h*ay);
+    world_fill_rect(id, x-w2, y-h2, w, h, proc);
+}
+
+static WORLD_BLOCK_OBSERVER(shaper) {
+    uint32_t biome = blocks_get_biome(id);
+    uint32_t kind = blocks_get_kind(id);
+    uint32_t old_biome = blocks_get_biome(world[block_idx]);
+    uint32_t old_kind = blocks_get_kind(world[block_idx]);
+
+    if (biome == old_biome) {
+        if (kind == BLOCK_KIND_WALL && kind == old_kind) {
+            return blocks_find(biome, BLOCK_KIND_HILL);
+        }
+    }
+
+    return id;
 }
 
 int32_t world_gen(int32_t seed) {
@@ -27,13 +53,18 @@ int32_t world_gen(int32_t seed) {
     uint32_t watr_id = blocks_find(BLOCK_BIOME_DEV, BLOCK_KIND_WATER);
 
     // walls
-    world_fill_rect(wall_id, 0, 0, world_width, world_height);
+    world_fill_rect(wall_id, 0, 0, world_width, world_height, NULL);
 
     // ground
-    world_fill_rect(grnd_id, 1, 1, world_width-2, world_height-2);
+    world_fill_rect(grnd_id, 1, 1, world_width-2, world_height-2, NULL);
 
     // water
-    world_fill_dot(watr_id, 8, 8, 4, 4);
+    world_fill_rect_anchor(watr_id, 8, 8, 4, 4, 0.5f, 0.5f, NULL);
+
+    // hills
+    world_fill_rect_anchor(wall_id, 14, 21, 8, 8, 0.5f, 0.5f, shaper);
+    world_fill_rect_anchor(wall_id, 14, 21, 4, 4, 0.5f, 0.5f, shaper);
+
 
     return WORLD_ERROR_NONE;
 }