diff --git a/runtime/lib/runtime.rb b/runtime/lib/runtime.rb
new file mode 100644
index 0000000..736d8c1
--- /dev/null
+++ b/runtime/lib/runtime.rb
@@ -0,0 +1,71 @@
+module Runtime
+  class << self
+
+    # Return the base paths to the runtime directories.
+    #
+    # @return [Array] Current runtime paths.
+    def paths
+      @paths ||= default_paths
+    end
+
+    # Find a runtime file.
+    #
+    # @param type [Symbol]
+    #   Type of runtime file to find. Options:
+    #   - :shader
+    #   - :font
+    # @param name [String]
+    #   Name of the runtime file to locate.
+    #
+    # @return [String, nil]
+    #   Path to the runtime file, or +nil+ if not found.
+    def find(type, name)
+      path = nil
+      paths.find do |runtime_path|
+        path = find_in(type, name, runtime_path)
+      end
+      path
+    end
+
+    private
+
+    # Return the default runtime paths.
+    #
+    # @return [Array] Default runtime paths.
+    def default_paths
+      [
+        File.expand_path("~/.jes"),
+        File.expand_path("../../runtime", $0),
+      ]
+    end
+
+    # Find a runtime file within a single runtime path.
+    #
+    # @param type [Symbol]
+    #   Type of runtime file to find. Options:
+    #   - :shader
+    #   - :font
+    # @param name [String]
+    #   Name of the runtime file to locate.
+    # @param runtime_path [String]
+    #   The runtime path to look in.
+    #
+    # @return [String, nil]
+    #   Path to the runtime file, or +nil+ if not found.
+    def find_in(type, name, runtime_path)
+      path =
+        case type
+        when :shader
+          File.join(runtime_path, "shaders", name)
+        else
+          raise "Unknown runtime type: #{type.inspect}"
+        end
+      if File.exists?(path)
+        path
+      else
+        nil
+      end
+    end
+
+  end
+end
diff --git a/runtime/main.rb b/runtime/main.rb
index f50f476..ea1dd16 100644
--- a/runtime/main.rb
+++ b/runtime/main.rb
@@ -1,6 +1,14 @@
-def main
-  puts "hi from main.rb"
-  p ARGV
+def init_loadpath
+  $LOAD_PATH.unshift(File.expand_path("../../runtime/lib", $0))
 end
 
-main
+def load_lib_files
+  require "runtime"
+end
+
+def main(argv)
+  init_loadpath
+  load_lib_files
+end
+
+main(ARGV)