diff --git a/src/generator.h b/src/generator.h
index 31c6b17..6c3b8ff 100644
--- a/src/generator.h
+++ b/src/generator.h
@@ -57,7 +57,7 @@ struct MultiPathCarver
     void force_to_match(int face);
 
     /* Add the next set of platforms (all at z) to the level. */
-    void next(struct level *level, num z, num length);
+    void next(struct level *level, num z, num length, num height=0.0);
 
 private:
     struct Path {
@@ -134,6 +134,7 @@ struct AcceleronGenerator: public Generator
 
     num generate_ascending_funnel(struct level *level, num z);
     num generate_tunnel_block(struct level *level, num z, int sections);
+    num generate_fractured_tunnel(struct level *level, num z, int sections);
 
     void change_phase(void);
 
diff --git a/src/generator/gen2.cpp b/src/generator/gen2.cpp
index abdbf69..51ded41 100644
--- a/src/generator/gen2.cpp
+++ b/src/generator/gen2.cpp
@@ -11,6 +11,7 @@
 #define P_ASCF_RED               num(0.2)
 #define P_TUNNEL_RED             num(0.2)
 #define P_TUNNEL_RED_RING        num(0.15)
+#define P_TUNNEL_BLUE            num(0.05)
 
 AcceleronGenerator::AcceleronGenerator():
     m_checkerboard_carver{3}
@@ -123,6 +124,16 @@ num AcceleronGenerator::generate_ascending_funnel(struct level *level, num z)
     return z;
 }
 
+static platform_type_t tunnel_type(void)
+{
+    if(num_rand() <= P_TUNNEL_BLUE)
+        return PLATFORM_BLUE;
+    else if(num_rand() <= P_TUNNEL_RED)
+        return PLATFORM_RED;
+    else
+        return PLATFORM_WHITE;
+}
+
 /* Generates a tunnel block, which is full ring alternating with half rings.
    The total length (which should be odd) is specified as a parameter.
 
@@ -133,8 +144,8 @@ num AcceleronGenerator::generate_ascending_funnel(struct level *level, num z)
     ########## [h=0]
     (...repeats)
 
-   There is a random probability for any of the platforms to be red, and also a
-   random probability for entire rings to be red. */
+   There is a random probability for any of the platforms to be red or blue,
+   and also a random probability for entire rings to be red. */
 
 num AcceleronGenerator::generate_tunnel_block(struct level *level, num z,
     int sec)
@@ -151,7 +162,7 @@ num AcceleronGenerator::generate_tunnel_block(struct level *level, num z,
                 continue;
 
             struct platform p;
-            p.type = (num_rand() <= P_TUNNEL_RED) ? PLATFORM_RED : type;
+            p.type = (type == PLATFORM_WHITE) ? tunnel_type() : type;
             p.face = j;
             p.z = z;
             p.length = len;
@@ -164,6 +175,55 @@ num AcceleronGenerator::generate_tunnel_block(struct level *level, num z,
     return z;
 }
 
+/* Generates a fractured tunnel, which is a full ring followed by random-length
+   platforms varying between 0 and 3 units. This is repeated for as many
+   sections as requested.
+
+    0123456789
+    ########## [h=0]
+    ##..###.## [h=0]
+    ||#.||.#|.
+    .|..|..|..
+    (...repeats)
+
+   There is a random probability for any of the platforms to be red or blue. */
+num AcceleronGenerator::generate_fractured_tunnel(struct level *level, num z,
+    int sec)
+{
+    for(int i = 0; i < sec; i++) {
+        /* Initial ring */
+        for(int j = 0; j < PLATFORM_COUNT; j++) {
+            struct platform p;
+            p.type = tunnel_type();
+            p.face = j;
+            p.z = z;
+            p.length = G_PLATFORM_LEN;
+            p.height = 0;
+            add(level, p);
+        }
+
+        /* Fractured ring */
+        for(int j = 0; j < PLATFORM_COUNT; j++) {
+            int start = (num_rand() <= num(0.3)) ? 1 : 0;
+            int length = rand() % (4 - start);
+            if(!length)
+                continue;
+
+            struct platform p;
+            p.type = tunnel_type();
+            p.face = j;
+            p.z = z + (start + 1) * G_PLATFORM_LEN;
+            p.length = length * G_PLATFORM_LEN;
+            p.height = 0;
+            add(level, p);
+        }
+
+        z += 4 * G_PLATFORM_LEN;
+    }
+
+    return z;
+}
+
 void AcceleronGenerator::change_phase(void)
 {
     static int const freq_table[] = {
@@ -253,7 +313,7 @@ void AcceleronGenerator::generate(struct level *level)
 
                where you can't side-jump from the middle platform to the left
                one because the wall prevents it. */
-            bool walls = (i == 2 || i == 5 || i == 8 || i == 1);
+            bool walls = (i == 2 || i == 5 || i == 8 || i == 11);
 
             /* Start by excluding platforms from iteration #i */
             if(walls) {
@@ -265,7 +325,9 @@ void AcceleronGenerator::generate(struct level *level)
             }
 
             /* Advance */
-            m_checkerboard_carver.next(level, m_z, G_PLATFORM_LEN);
+            int height = (i == 13) ? 2 : (i == 12) ? 1 : (i / 3);
+            m_checkerboard_carver.next(level, m_z, G_PLATFORM_LEN,
+                height * PLATFORM_HEIGHT_STEP);
 
             /* Generate blocks and walls */
             if(walls) {
@@ -309,21 +371,13 @@ void AcceleronGenerator::generate(struct level *level)
 
     /* Phase #4: Incomplete tunnel block */
     else if(m_phase == 4) {
-        // TODO
+        m_z = this->generate_fractured_tunnel(level, m_z, 3);
         this->change_phase();
     }
 
-    /* Phase #1: Almost-full tunnel with random holes? */
-
-    /* Phase #2: Path with spacing + random onlookers */
-
-    /* Phase #3: Full + odd + even tunnel combination leading into #0 */
-
-
-    /* Phase #5: Obstacles
+    /* Phase #5: Fixed obstacles
        - ##.##.#.#.
        - .##.##.#.#
        - ..#..#..#.
        - .#..#..#.. */
-
 }
diff --git a/src/generator/path.cpp b/src/generator/path.cpp
index acd75df..10ff368 100644
--- a/src/generator/path.cpp
+++ b/src/generator/path.cpp
@@ -89,7 +89,7 @@ void MultiPathCarver::force_to_match(int face)
     }
 }
 
-void MultiPathCarver::next(struct level *level, num z, num length)
+void MultiPathCarver::next(struct level *level, num z, num length, num height)
 {
     /* Decide whether to skip */
     for(int i = 0; i < m_N; i++) {
@@ -108,7 +108,7 @@ void MultiPathCarver::next(struct level *level, num z, num length)
             p.face = face;
             p.z = z;
             p.length = length;
-            p.height = 0;
+            p.height = height;
             p.type = PLATFORM_WHITE;
             level->platform_buffer.push_back(p);
         }
diff --git a/src/render.cpp b/src/render.cpp
index 0db36fc..66f1e14 100644
--- a/src/render.cpp
+++ b/src/render.cpp
@@ -153,8 +153,10 @@ uint16_t render_platform_color(struct platform const *p,
         return camera_platform_color(camera, p->face);
     if(p->type == PLATFORM_BLUE)
         return render_color_blue_platform(t);
-    if(p->type == PLATFORM_SEPARATING_WALL || p->type == PLATFORM_BLOCK_TOP)
+    if(p->type == PLATFORM_SEPARATING_WALL)
         return RGB24(0x909090);
+    if(p->type == PLATFORM_BLOCK_TOP)
+        return RGB24(0xa0a0a0);
     if(p->type == PLATFORM_BLOCK)
         return RGB24(0x808080);
     if(p->type == PLATFORM_RED) {