diff --git a/assets/tiles/io_tile_off.png b/assets/tiles/io_tile_off.png
index afe0ffd..88872bd 100644
Binary files a/assets/tiles/io_tile_off.png and b/assets/tiles/io_tile_off.png differ
diff --git a/assets/tiles/io_tile_on.png b/assets/tiles/io_tile_on.png
index b543a9f..0ad849b 100644
Binary files a/assets/tiles/io_tile_on.png and b/assets/tiles/io_tile_on.png differ
diff --git a/src/editor.rs b/src/editor.rs
index e1877b3..8fbbd59 100644
--- a/src/editor.rs
+++ b/src/editor.rs
@@ -444,23 +444,20 @@ impl Editor {
 	}
 
 	pub fn draw(&mut self, d: &mut RaylibDrawHandle, textures: &Textures) {
-		d.clear_background(gray(48));
+		d.clear_background(BG_WORLD);
 
-		if self.draw_overlay && self.zoom >= 1. {
-			let tile_size = (TILE_TEXTURE_SIZE * self.zoom) as f32;
+		if self.draw_overlay && self.zoom >= 0.5 {
+			let tile_size = TILE_TEXTURE_SIZE * self.zoom;
 			let grid_spill_x = (self.view_offset.x).rem(tile_size) - tile_size;
 			let grid_spill_y = (self.view_offset.y).rem(tile_size) - tile_size;
-			d.gui_grid(
-				Rectangle::new(
-					grid_spill_x,
-					grid_spill_y,
-					d.get_screen_width() as f32 * 2.,
-					d.get_screen_height() as f32 * 2.,
-				),
-				None,
-				tile_size,
-				1,
-			);
+			for y in 0..=(d.get_screen_height() / tile_size as i32) {
+				let y = y * tile_size as i32 + grid_spill_y as i32;
+				d.draw_line(0, y, d.get_screen_width(), y, FG_GRID);
+			}
+			for x in 0..=(d.get_screen_width() / tile_size as i32) {
+				let x = x * tile_size as i32 + grid_spill_x as i32;
+				d.draw_line(x, 0, x, d.get_screen_height(), FG_GRID);
+			}
 		}
 
 		self.draw_board(d, textures);
diff --git a/src/marble_engine.rs b/src/marble_engine.rs
index f99ddd2..422301e 100644
--- a/src/marble_engine.rs
+++ b/src/marble_engine.rs
@@ -179,25 +179,6 @@ impl Machine {
 			};
 		}
 
-		for &(pos, _val, _dir) in &new_marbles {
-			let Some(Tile::Open(OpenTile::Blank, claim)) = self.board.get_mut(pos) else {
-				unreachable!()
-			};
-			*claim = match claim {
-				Claim::Free => Claim::Claimed,
-				Claim::Claimed | Claim::Blocked => Claim::Blocked,
-				_ => unreachable!(),
-			}
-		}
-		// new marbles are past old_marbles index, so will not move this step
-		for (pos, value, dir) in new_marbles {
-			let Some(Tile::Open(OpenTile::Blank, Claim::Claimed)) = self.board.get_mut(pos) else {
-				continue;
-			};
-			self.board.set(pos, Tile::Marble { value, dir });
-			self.marbles.push(pos);
-		}
-
 		// old wires have to be reset after machine processing,
 		// so they can figure out which directions they are powered from
 		for &p in &self.powered {
@@ -220,7 +201,7 @@ impl Machine {
 			Multiple,
 		}
 
-		// find all direct bounces
+		// #### find all direct bounces ####
 		let mut will_reverse_direction = vec![false; self.marbles.len()];
 		// todo store in tile to remove search through self.marbles
 		let mut influenced_direction = vec![DirInfluence::None; self.marbles.len()];
@@ -261,7 +242,7 @@ impl Machine {
 				_ => (),
 			}
 		}
-		// apply all direct bounces
+		// #### apply all direct bounces ####
 		for (i, &pos) in self.marbles.iter().enumerate() {
 			let Some(Tile::Marble { value: _, dir }) = self.board.get_mut(pos) else {
 				unreachable!()
@@ -273,6 +254,29 @@ impl Machine {
 			}
 		}
 
+		// #### new marbles ####
+		// prepare creating the new marbles
+		for &(pos, _val, _dir) in &new_marbles {
+			let Some(Tile::Open(OpenTile::Blank, claim)) = self.board.get_mut(pos) else {
+				unreachable!()
+			};
+			*claim = match claim {
+				Claim::Free => Claim::Claimed,
+				Claim::Claimed | Claim::Blocked => Claim::Blocked,
+				_ => unreachable!(),
+			}
+		}
+		// create new marbles
+		// new marbles are past old_marbles index, so will not move this step
+		for (pos, value, dir) in new_marbles {
+			let Some(Tile::Open(OpenTile::Blank, Claim::Claimed)) = self.board.get_mut(pos) else {
+				continue;
+			};
+			self.board.set(pos, Tile::Marble { value, dir });
+			self.marbles.push(pos);
+		}
+
+		// #### movement ####
 		let mut claim_positions = Vec::new();
 		// mark claims to figure out what spaces can be moved to
 		for &pos in &self.marbles[..old_marbles] {
diff --git a/src/theme.rs b/src/theme.rs
index 6d9cdc8..fd2875c 100644
--- a/src/theme.rs
+++ b/src/theme.rs
@@ -1,5 +1,8 @@
 use raylib::prelude::*;
 
+pub const BG_WORLD: Color = gray(48);
+pub const FG_GRID: Color = gray(64);
+
 pub const BG_DARK: Color = gray(32);
 pub const BG_MEDIUM: Color = gray(48);
 pub const BG_LIGHT: Color = gray(64);