diff --git a/assets/asm/mosaic_change.asm b/assets/asm/mosaic_change.asm
new file mode 100644
index 00000000..ab7ff135
--- /dev/null
+++ b/assets/asm/mosaic_change.asm
@@ -0,0 +1,53 @@
+
+    JML AreaCheck
+
+AreaCheck:
+{
+    PHB : PHK : PLB
+
+    TAX
+    LDA .pool, X
+
+    BEQ .noMosaic1
+        PLB
+        JML $02AAE5
+
+    .noMosaic1
+
+    LDX $8A
+    LDA .pool, X
+
+    BEQ .noMosaic2
+        PLB
+        JML $02AAE5
+
+    .noMosaic2
+
+    PLB
+    JML $02AAF4
+
+    .pool
+    ;LW
+    db $01, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    ;DW
+    db $01, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    ;SP
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+    db $00, $00, $00, $00, $00, $00, $00, $00
+}
\ No newline at end of file
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 8bed4879..cd190498 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,5 +1,3 @@
-include_directories(lib/cmake)
-
 # gui libraries ---------------------------------------------------------------
 set(IMGUI_PATH  "lib/imgui")
 file(GLOB IMGUI_SOURCES ${IMGUI_PATH}/*.cpp)
@@ -23,9 +21,23 @@ target_include_directories(ImGuiColorTextEdit PUBLIC ${IMGUI_PATH})
 target_compile_definitions(ImGuiColorTextEdit PUBLIC 
   IMGUI_IMPL_OPENGL_LOADER_CUSTOM=<SDL2/SDL_opengl.h>  GL_GLEXT_PROTOTYPES=1)
 
-# asar assembly ---------------------------------------------------------------
+set(
+  IMGUI_SRC
+  ${IMGUI_PATH}/imgui.cpp 
+  ${IMGUI_PATH}/imgui_demo.cpp
+  ${IMGUI_PATH}/imgui_draw.cpp 
+  ${IMGUI_PATH}/imgui_widgets.cpp
+  ${IMGUI_PATH}/backends/imgui_impl_sdl.cpp
+  ${IMGUI_PATH}/backends/imgui_impl_sdlrenderer.cpp 
+  ${IMGUI_PATH}/misc/cpp/imgui_stdlib.cpp
+  ${IMGUI_FILE_DLG_PATH}/ImGuiFileDialog.cpp
+  ${IMGUI_COLOR_TEXT_EDIT_PATH}/TextEditor.cpp
+)
+
+# Asar Assembly ---------------------------------------------------------------
+add_subdirectory(lib/asar/src)
 get_target_property(ASAR_INCLUDE_DIR asar-static INCLUDE_DIRECTORIES)
-include_directories(${ASAR_INCLUDE_DIR})
+add_definitions(-Dstricmp=strcasecmp)
 
 # executable linkage ----------------------------------------------------------
 
@@ -60,34 +72,36 @@ set(
   app/zelda3/screen.cc
 )
 
-add_executable(
-    yaze
-    yaze.cc
-    ${YAZE_APP_CORE_SRC}
-    ${YAZE_APP_EDITOR_SRC}
-    ${YAZE_APP_GFX_SRC}
-    ${YAZE_APP_ZELDA3_SRC}
-    app/rom.cc
-    gui/canvas.cc
-    gui/input.cc
-    gui/style.cc
-    gui/widgets.cc
-    # GUI libraries 
-    ${IMGUI_PATH}/imgui.cpp 
-    ${IMGUI_PATH}/imgui_demo.cpp
-    ${IMGUI_PATH}/imgui_draw.cpp 
-    ${IMGUI_PATH}/imgui_widgets.cpp
-    ${IMGUI_PATH}/backends/imgui_impl_sdl.cpp
-    ${IMGUI_PATH}/backends/imgui_impl_sdlrenderer.cpp 
-    ${IMGUI_PATH}/misc/cpp/imgui_stdlib.cpp
-    ${IMGUI_FILE_DLG_PATH}/ImGuiFileDialog.cpp
-    ${IMGUI_COLOR_TEXT_EDIT_PATH}/TextEditor.cpp
+set(
+  YAZE_APP_ASM_SRC
+  app/asm/script.cc
 )
 
+set(
+  YAZE_GUI_SRC
+  gui/canvas.cc
+  gui/input.cc
+  gui/style.cc
+  gui/widgets.cc
+)
+
+add_executable(
+  yaze
+  yaze.cc
+  app/rom.cc
+  ${YAZE_APP_ASM_SRC}
+  ${YAZE_APP_CORE_SRC}
+  ${YAZE_APP_EDITOR_SRC}
+  ${YAZE_APP_GFX_SRC}
+  ${YAZE_APP_ZELDA3_SRC}
+  ${YAZE_GUI_SRC}
+  ${IMGUI_SRC}
+
 target_include_directories(
   yaze PUBLIC
   lib/
   app/
+  ${ASAR_INCLUDE_DIR}
   ${CMAKE_SOURCE_DIR}/src/
   ${PNG_INCLUDE_DIRS}
   ${SDL2_INCLUDE_DIR}
diff --git a/src/app/asm/script.cc b/src/app/asm/script.cc
new file mode 100644
index 00000000..6bf86938
--- /dev/null
+++ b/src/app/asm/script.cc
@@ -0,0 +1,45 @@
+#include "script.h"
+
+#include <interface-lib.h>
+
+#include <array>
+#include <fstream>
+#include <sstream>
+
+#include "absl/status/status.h"
+#include "absl/status/statusor.h"
+#include "absl/strings/string_view.h"
+#include "app/core/constants.h"
+#include "app/rom.h"
+
+namespace yaze {
+namespace app {
+namespace snes_asm {
+
+absl::Status Script::ApplyPatchToROM(ROM& rom) {
+  if (!asar_patch(patch_filename_, rom_.data(), patch_size_, rom_.size())) {
+    return absl::InternalError("Unable to apply patch");
+  }
+  return absl::OkStatus();
+}
+
+absl::StatusOr<absl::string_view> Script::GenerateMosaicChangeAssembly(
+    std::array<int, core::kNumOverworldMaps> mosaic_tiles) {
+  std::fstream file("assets/asm/mosaic_change.asm",
+                    std::ios::out | std::ios::in);
+  if (!file.is_open()) {
+    return absl::InvalidArgumentError(
+        "Couldn't open mosaic change template file");
+  }
+  std::stringstream assembly;
+  assembly << "org ";
+  assembly << kDefaultMosaicHook;
+  assembly << file.rdbuf();
+
+  file.close();
+  return assembly.str();
+}
+
+}  // namespace snes_asm
+}  // namespace app
+}  // namespace yaze
\ No newline at end of file
diff --git a/src/app/asm/script.h b/src/app/asm/script.h
new file mode 100644
index 00000000..6d131551
--- /dev/null
+++ b/src/app/asm/script.h
@@ -0,0 +1,41 @@
+#ifndef YAZE_APP_ASM_SCRIPT_H
+#define YAZE_APP_ASM_SCRIPT_H
+
+#include <interface-lib.h>
+
+#include <array>
+#include <fstream>
+#include <sstream>
+
+#include "absl/status/status.h"
+#include "absl/status/statusor.h"
+#include "absl/strings/string_view.h"
+#include "app/core/constants.h"
+#include "app/rom.h"
+
+namespace yaze {
+namespace app {
+namespace snes_asm {
+
+constexpr char kDefaultMosaicHook[] = "$02AADB";
+
+class Script {
+ public:
+  Script() = default;
+
+  absl::Status ApplyPatchToROM(ROM& rom);
+
+  absl::StatusOr<absl::string_view> GenerateMosaicChangeAssembly(
+      std::array<int, core::kNumOverworldMaps> mosaic_tiles);
+
+ private:
+  int64_t patch_size_;
+  std::string patch_filename_;
+  std::string patch_contents_;
+};
+
+}  // namespace snes_asm
+}  // namespace app
+}  // namespace yaze
+
+#endif
\ No newline at end of file
diff --git a/src/app/core/constants.h b/src/app/core/constants.h
index 55a0e640..54eba4c7 100644
--- a/src/app/core/constants.h
+++ b/src/app/core/constants.h
@@ -89,10 +89,10 @@ constexpr int NumberOfSheets = 223;
 constexpr int LimitOfMap32 = 8864;
 constexpr int NumberOfRooms = 296;
 
-constexpr int NumberOfOWMaps = 160;
+constexpr int kNumOverworldMaps = 160;
 constexpr int Map32PerScreen = 256;
 constexpr int NumberOfMap16 = 3752;  // 4096
-constexpr int NumberOfMap32 = Map32PerScreen * NumberOfOWMaps;
+constexpr int NumberOfMap32 = Map32PerScreen * kNumOverworldMaps;
 constexpr int NumberOfOWSprites = 352;
 constexpr int NumberOfColors = 3143;
 
diff --git a/src/app/editor/overworld_editor.cc b/src/app/editor/overworld_editor.cc
index e76d4d5b..8005f8a9 100644
--- a/src/app/editor/overworld_editor.cc
+++ b/src/app/editor/overworld_editor.cc
@@ -11,6 +11,7 @@
 #include "app/gfx/bitmap.h"
 #include "app/gfx/snes_palette.h"
 #include "app/gfx/snes_tile.h"
+#include "app/rom.h"
 #include "app/zelda3/overworld.h"
 #include "gui/canvas.h"
 #include "gui/icons.h"
diff --git a/src/app/editor/overworld_editor.h b/src/app/editor/overworld_editor.h
index 48aca883..fe5f4407 100644
--- a/src/app/editor/overworld_editor.h
+++ b/src/app/editor/overworld_editor.h
@@ -11,6 +11,7 @@
 #include "app/gfx/bitmap.h"
 #include "app/gfx/snes_palette.h"
 #include "app/gfx/snes_tile.h"
+#include "app/rom.h"
 #include "app/zelda3/overworld.h"
 #include "gui/canvas.h"
 #include "gui/icons.h"
diff --git a/src/app/editor/screen_editor.cc b/src/app/editor/screen_editor.cc
index 7dfd72d0..14e533fb 100644
--- a/src/app/editor/screen_editor.cc
+++ b/src/app/editor/screen_editor.cc
@@ -2,6 +2,15 @@
 
 #include <imgui/imgui.h>
 
+#include <algorithm>
+#include <fstream>
+#include <iostream>
+#include <sstream>
+#include <string>
+
+#include "absl/status/statusor.h"
+#include "absl/strings/string_view.h"
+#include "app/asm/script.h"
 #include "app/core/common.h"
 #include "app/core/constants.h"
 #include "app/gfx/bitmap.h"
@@ -16,6 +25,7 @@ ScreenEditor::ScreenEditor() { screen_canvas_.SetCanvasSize(ImVec2(512, 512)); }
 
 void ScreenEditor::Update() {
   TAB_BAR("##TabBar")
+  DrawMosaicEditor();
   DrawTitleScreenEditor();
   DrawNamingScreenEditor();
   DrawOverworldMapEditor();
@@ -25,6 +35,20 @@ void ScreenEditor::Update() {
   END_TAB_BAR()
 }
 
+void ScreenEditor::DrawMosaicEditor() {
+  TAB_ITEM("Mosaic Transitions")
+  if (ImGui::Button("GenerateMosaicChangeAssembly")) {
+    auto mosaic = mosaic_script_.GenerateMosaicChangeAssembly(mosaic_tiles_);
+    if (!mosaic.ok()) {
+      std::cout << "Failed to generate mosaic change assembly";
+    } else {
+      std::cout << "Successfully generated mosaic change assembly";
+      std::cout << mosaic.value();
+    }
+  }
+  END_TAB_ITEM()
+}
+
 void ScreenEditor::DrawTitleScreenEditor() {
   TAB_ITEM("Title Screen")
   END_TAB_ITEM()
diff --git a/src/app/editor/screen_editor.h b/src/app/editor/screen_editor.h
index 23a56c4b..bd9a900c 100644
--- a/src/app/editor/screen_editor.h
+++ b/src/app/editor/screen_editor.h
@@ -3,6 +3,10 @@
 
 #include <imgui/imgui.h>
 
+#include <array>
+
+#include "app/asm/script.h"
+#include "app/core/constants.h"
 #include "app/gfx/bitmap.h"
 #include "app/gfx/snes_tile.h"
 #include "app/zelda3/screen.h"
@@ -12,12 +16,15 @@ namespace yaze {
 namespace app {
 namespace editor {
 
+using MosaicArray = std::array<int, core::kNumOverworldMaps>;
+
 class ScreenEditor {
  public:
   ScreenEditor();
   void Update();
 
  private:
+  void DrawMosaicEditor();
   void DrawTitleScreenEditor();
   void DrawNamingScreenEditor();
   void DrawOverworldMapEditor();
@@ -28,6 +35,8 @@ class ScreenEditor {
   void DrawCanvas();
   void DrawToolset();
 
+  std::array<int, core::kNumOverworldMaps> mosaic_tiles_;
+  snes_asm::Script mosaic_script_;
   zelda3::Screen current_screen_;
   gui::Canvas screen_canvas_;
 };
diff --git a/src/app/zelda3/overworld.cc b/src/app/zelda3/overworld.cc
index ac323edd..6cad4655 100644
--- a/src/app/zelda3/overworld.cc
+++ b/src/app/zelda3/overworld.cc
@@ -18,13 +18,13 @@ absl::Status Overworld::Load(ROM &rom, uchar *ow_blockset) {
     return decompression_status;
   }
 
-  for (int map_index = 0; map_index < core::NumberOfOWMaps; ++map_index)
+  for (int map_index = 0; map_index < core::kNumOverworldMaps; ++map_index)
     overworld_maps_.emplace_back(map_index, rom_, tiles16);
 
   FetchLargeMaps();
 
   auto size = tiles16.size();
-  for (int i = 0; i < core::NumberOfOWMaps; ++i) {
+  for (int i = 0; i < core::kNumOverworldMaps; ++i) {
     auto map_status =
         overworld_maps_[i].BuildMapV2(size, game_state_, map_parent_);
     if (!map_status.ok()) {
diff --git a/src/lib/SDL b/src/lib/SDL
index adb3e1a2..5858c7df 160000
--- a/src/lib/SDL
+++ b/src/lib/SDL
@@ -1 +1 @@
-Subproject commit adb3e1a21d381cc1e62a12ae41cc7e5585c72a92
+Subproject commit 5858c7dfce80b0854b04475dde97996692ce9200
diff --git a/src/lib/abseil-cpp b/src/lib/abseil-cpp
index 701185db..0c923304 160000
--- a/src/lib/abseil-cpp
+++ b/src/lib/abseil-cpp
@@ -1 +1 @@
-Subproject commit 701185dbce17a2f49334027ca3cb5788a5d06c6d
+Subproject commit 0c92330442d6b1be934e0407115c8084250ef347
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index aa049b21..66023f68 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -15,6 +15,7 @@ add_executable(
   yaze_test.cc
   rom_test.cc
   ../src/app/rom.cc
+  ../src/app/asm/script.cc
   ../src/app/gfx/bitmap.cc
   ../src/app/gfx/snes_tile.cc
   ../src/app/gfx/snes_palette.cc
@@ -43,6 +44,7 @@ target_link_libraries(
   absl::raw_logging_internal
   SDL2::SDL2
   ${OPENGL_LIBRARIES}
+  asar-static
   gmock_main
   gmock
   gtest_main