diff --git a/collision.py b/collision.py
index 05cfbf8..c18af9a 100644
--- a/collision.py
+++ b/collision.py
@@ -475,7 +475,7 @@ class CollisionLord:
 
     def update(self):
         "Resolve overlaps between all relevant world objects."
-        for i in range(self.iterations):
+        for _ in range(self.iterations):
             # filter shape lists for anything out of room etc
             valid_dynamic_shapes = []
             for shape in self.dynamic_shapes:
diff --git a/edit_command.py b/edit_command.py
index 75def5e..e470e14 100644
--- a/edit_command.py
+++ b/edit_command.py
@@ -15,7 +15,7 @@ class EditCommand:
         for frame in self.tile_commands.values():
             for layer in frame.values():
                 for column in layer.values():
-                    for tile in column.values():
+                    for _tile in column.values():
                         commands += 1
         return commands
 
diff --git a/game_object.py b/game_object.py
index 404f6ed..01a67bc 100644
--- a/game_object.py
+++ b/game_object.py
@@ -1082,7 +1082,7 @@ class GameObject:
         steps = int(total_move_dist / step_dist)
         # start stepping from beginning of this frame's move distance
         self.x, self.y = self.last_x, self.last_y
-        for i in range(steps):
+        for _ in range(steps):
             self.x += dir_x * step_dist
             self.y += dir_y * step_dist
             collisions = self.get_collisions()
diff --git a/games/crawler/scripts/topview.py b/games/crawler/scripts/topview.py
index 0bf2815..24bedec 100644
--- a/games/crawler/scripts/topview.py
+++ b/games/crawler/scripts/topview.py
@@ -41,7 +41,7 @@ class CrawlTopDownView(GameObject):
         # make a copy of original layer to color for visibility, hide original
         self.art.duplicate_layer(0)
         self.art.layers_visibility[0] = False
-        for frame, layer, x, y in TileIter(self.art):
+        for _frame, layer, x, y in TileIter(self.art):
             if layer == 0:
                 continue
             # set all tiles undiscovered
diff --git a/games/fireplace/scripts/fireplace.py b/games/fireplace/scripts/fireplace.py
index a8b5f0b..0e8c4b3 100644
--- a/games/fireplace/scripts/fireplace.py
+++ b/games/fireplace/scripts/fireplace.py
@@ -66,7 +66,7 @@ class Fireplace(GameObject):
         self.weighted_chars = sorted(chars, key=weights.__getitem__)
         # spawn initial particles
         self.particles = []
-        for i in range(self.target_particles):
+        for _ in range(self.target_particles):
             p = FireParticle(self)
             self.particles.append(p)
         # help screen
diff --git a/games/wildflowers/scripts/petal.py b/games/wildflowers/scripts/petal.py
index 0f0698a..a692881 100644
--- a/games/wildflowers/scripts/petal.py
+++ b/games/wildflowers/scripts/petal.py
@@ -130,7 +130,7 @@ class Petal:
         tiles = []
         angle = 0
         resolution = 30
-        for i in range(resolution):
+        for _ in range(resolution):
             angle += math.radians(90.0 / resolution)
             x = round(math.cos(angle) * self.radius)
             y = round(math.sin(angle) * self.radius)
diff --git a/image_convert.py b/image_convert.py
index a721057..a74e0a7 100644
--- a/image_convert.py
+++ b/image_convert.py
@@ -155,7 +155,7 @@ class ImageConverter:
     def update(self):
         if time.time() < self.start_time + self.start_delay:
             return
-        for i in range(self.tiles_per_tick):
+        for _ in range(self.tiles_per_tick):
             x_start, y_start = self.x * self.char_w, self.y * self.char_h
             x_end, y_end = x_start + self.char_w, y_start + self.char_h
             block = self.src_array[y_start:y_end, x_start:x_end]
@@ -198,8 +198,8 @@ class ImageConverter:
             color_counts += [(color, counts[i])]
         color_counts.sort(key=lambda item: item[1], reverse=True)
         combos = []
-        for color1, count1 in color_counts:
-            for color2, count2 in color_counts:
+        for color1, _count1 in color_counts:
+            for color2, _count2 in color_counts:
                 if color1 == color2:
                     continue
                 # fg/bg color swap SHOULD be allowed
diff --git a/image_export.py b/image_export.py
index a14ee90..8f883df 100644
--- a/image_export.py
+++ b/image_export.py
@@ -143,7 +143,6 @@ def export_still_image(app, art, out_filename, crt=True, scale=1, bg_color=None)
         if not src_img:
             return False
         src_img.save(out_filename, "PNG")
-        output_format = "32-bit w/ alpha"
     else:
         # else convert to current palette.
         # as with aniGIF export, use arbitrary color for transparency
diff --git a/palette.py b/palette.py
index f470563..16db86f 100644
--- a/palette.py
+++ b/palette.py
@@ -28,10 +28,8 @@ class PaletteLord:
         ):
             return
         self.last_check = self.app.get_elapsed_time()
-        changed = None
         for palette in self.app.palettes:
             if palette.has_updated():
-                changed = palette.filename
                 try:
                     palette.load_image()
                     self.app.log(
diff --git a/renderable.py b/renderable.py
index 95d907a..6efd905 100644
--- a/renderable.py
+++ b/renderable.py
@@ -101,10 +101,12 @@ class TileRenderable:
 
     def __str__(self):
         "for debug purposes, return a concise unique name"
-        i = 0
-        for i, r in enumerate(self.art.renderables):
+        for idx, r in enumerate(self.art.renderables):
             if r is self:
+                i = idx
                 break
+        else:
+            i = 0
         return "{} {} {}".format(self.art.get_simple_name(), self.__class__.__name__, i)
 
     def create_buffers(self):
@@ -546,7 +548,6 @@ class TileRenderable:
             if not self.app.show_hidden_layers and not self.art.layers_visibility[i]:
                 continue
             layer_start = i * layer_size
-            layer_end = layer_start + layer_size
             # for active art, dim all but active layer based on UI setting
             if (
                 not self.app.game_mode
diff --git a/renderable_line.py b/renderable_line.py
index f0ce1e7..02da38d 100644
--- a/renderable_line.py
+++ b/renderable_line.py
@@ -331,7 +331,6 @@ class DebugLineRenderable(WorldLineRenderable):
     def add_lines(self, new_verts, new_colors=None):
         "add lines to the current ones"
         line_items = len(self.vert_array)
-        lines = int(line_items / self.vert_items)
         # if new_verts is a list of tuples, unpack into flat list
         if type(new_verts[0]) is tuple:
             new_verts_unpacked = []
diff --git a/ui.py b/ui.py
index 31348ea..806d667 100644
--- a/ui.py
+++ b/ui.py
@@ -287,10 +287,12 @@ class UI:
             )
 
     def set_active_art_by_filename(self, art_filename):
-        i = 0
-        for i, art in enumerate(self.app.art_loaded_for_edit):
+        for idx, art in enumerate(self.app.art_loaded_for_edit):
             if art_filename == art.filename:
+                i = idx
                 break
+        else:
+            i = 0
         new_active_art = self.app.art_loaded_for_edit.pop(i)
         self.app.art_loaded_for_edit.insert(0, new_active_art)
         new_active_renderable = self.app.edit_renderables.pop(i)
diff --git a/ui_art_dialog.py b/ui_art_dialog.py
index bd8ac3f..ee7e1ae 100644
--- a/ui_art_dialog.py
+++ b/ui_art_dialog.py
@@ -626,7 +626,7 @@ class AddLayerDialog(UIDialog):
         if not valid_name:
             return False, self.name_exists_error
         try:
-            z = float(self.field_texts[1])
+            float(self.field_texts[1])
         except Exception:
             return False, self.invalid_z_error
         return True, None
@@ -684,7 +684,7 @@ class SetLayerZDialog(UIDialog):
 
     def is_input_valid(self):
         try:
-            z = float(self.field_texts[0])
+            float(self.field_texts[0])
         except Exception:
             return False, self.invalid_z_error
         return True, None
@@ -745,7 +745,7 @@ class PaletteFromFileDialog(UIDialog):
         src_filename = self.field_texts[0]
         palette_filename = self.field_texts[1]
         colors = int(self.field_texts[2])
-        new_pal = PaletteFromFile(self.ui.app, src_filename, palette_filename, colors)
+        PaletteFromFile(self.ui.app, src_filename, palette_filename, colors)
         self.dismiss()
 
 
diff --git a/ui_chooser_dialog.py b/ui_chooser_dialog.py
index 90269af..1eebf28 100644
--- a/ui_chooser_dialog.py
+++ b/ui_chooser_dialog.py
@@ -176,7 +176,7 @@ class ChooserDialog(UIDialog):
         # os.access(new_dir, os.R_OK) seems to always return True,
         # so try/catch listdir instead
         try:
-            l = os.listdir(new_dir)
+            os.listdir(new_dir)
         except PermissionError:
             line = "No permission to access {}!".format(os.path.abspath(new_dir))
             self.ui.message_line.post_line(line, error=True)
diff --git a/ui_console.py b/ui_console.py
index c15275c..4bf2c71 100644
--- a/ui_console.py
+++ b/ui_console.py
@@ -143,7 +143,7 @@ class ImportCommand(ConsoleCommand):
             )
         if not os.path.exists(filename):
             console.ui.app.log("Couldn't find file {}".format(filename))
-        importer = importer_class(console.ui.app, filename)
+        importer_class(console.ui.app, filename)
 
 
 class ExportCommand(ConsoleCommand):
@@ -162,7 +162,7 @@ class ExportCommand(ConsoleCommand):
             console.ui.app.log(
                 "Couldn't find exporter class {}".format(exporter_classname)
             )
-        exporter = exporter_class(console.ui.app, filename)
+        exporter_class(console.ui.app, filename)
 
 
 class PaletteFromImageCommand(ConsoleCommand):
diff --git a/ui_popup.py b/ui_popup.py
index 9414bce..7b77427 100644
--- a/ui_popup.py
+++ b/ui_popup.py
@@ -431,7 +431,7 @@ class ToolPopup(UIElement):
         # charset renderable location will be set in update()
         charset = self.ui.active_art.charset
         palette = self.ui.active_art.palette
-        cqw, cqh = (
+        _cqw, cqh = (
             self.charset_swatch.art.quad_width,
             self.charset_swatch.art.quad_height,
         )
diff --git a/ui_tool.py b/ui_tool.py
index 6e2074a..b89bf82 100644
--- a/ui_tool.py
+++ b/ui_tool.py
@@ -294,7 +294,6 @@ class TextTool(UITool):
         self.input_active = False
         self.ui.tool_settings_changed = True
         if self.cursor:
-            x, y = int(self.cursor.x) + 1, int(-self.cursor.y) + 1
             self.cursor.finish_paint()
         # self.ui.message_line.post_line('Finished text entry at %s, %s' % (x, y))
         self.ui.message_line.post_line("Finished text entry.")
diff --git a/vector.py b/vector.py
index b369c9b..cf6ef27 100644
--- a/vector.py
+++ b/vector.py
@@ -216,9 +216,9 @@ def world_to_screen(app, world_x, world_y, world_z):
     # viewport tuple order should be same as glGetFloatv(GL_VIEWPORT)
     viewport = (0, 0, app.window_width, app.window_height)
     try:
-        x, y, z = GLU.gluProject(world_x, world_y, world_z, vm, pjm, viewport)
+        x, y, _z = GLU.gluProject(world_x, world_y, world_z, vm, pjm, viewport)
     except Exception:
-        x, y, z = 0, 0, 0
+        x, y = 0, 0
         app.log("GLU.gluProject failed!")
     # does Z mean anything here?
     return x, y