A couple of terrain types added. First adventure added, incomplete.

src/bosses/adventure_system.nvgt

@@ -0,0 +1,81 @@
+// Adventure System
+// Handles triggering and managing terrain-specific adventures
+
+#include "src/bosses/unicorn/unicorn_boss.nvgt"
+
+void check_adventure_menu(int player_x) {
+    if (key_pressed(KEY_TAB)) {
+        run_adventure_menu(player_x);
+    }
+}
+
+void run_adventure_menu(int player_x) {
+    if (player_x <= BASE_END) {
+        speak_with_history("No adventures available in the base.", true);
+        return;
+    }
+
+    if (last_adventure_day == current_day) {
+        speak_with_history("You have already attempted an adventure today.", true);
+        return;
+    }
+
+    string terrain = get_terrain_at_position(player_x);
+    MountainRange@ mountain = get_mountain_at(player_x);
+    
+    // Check available adventures based on terrain
+    string[] options;
+    int[] adventure_ids; // 1 = Unicorn
+    
+    if (mountain !is null) {
+        // Mountain terrain
+        options.insert_last("Unicorn Hunt (Mountain Boss)");
+        adventure_ids.insert_last(1);
+    }
+    
+    if (options.length() == 0) {
+        speak_with_history("No adventures found in this area.", true);
+        return;
+    }
+    
+    // Show Menu
+    speak_with_history("Adventure Menu.", true);
+    int selection = 0;
+    speak_with_history(options[selection], true);
+    
+    while (true) {
+        wait(5);
+        
+        if (key_pressed(KEY_ESCAPE)) {
+            speak_with_history("Closed.", true);
+            return;
+        }
+        
+        if (key_pressed(KEY_DOWN)) {
+            selection++;
+            if (selection >= options.length()) selection = 0;
+            speak_with_history(options[selection], true);
+        }
+        
+        if (key_pressed(KEY_UP)) {
+            selection--;
+            if (selection < 0) selection = options.length() - 1;
+            speak_with_history(options[selection], true);
+        }
+        
+        if (key_pressed(KEY_RETURN)) {
+            start_adventure(adventure_ids[selection]);
+            // Adventure has finished (it blocks until done)
+            // Resume main game ambience
+            update_ambience(true);
+            return;
+        }
+    }
+}
+
+void start_adventure(int adventure_id) {
+    last_adventure_day = current_day;
+    if (adventure_id == 1) {
+        run_unicorn_adventure();
+    }
+}