diff --git a/levels/01-blob/win b/levels/01-blob/win
index 337555a..1232d11 100644
--- a/levels/01-blob/win
+++ b/levels/01-blob/win
@@ -1,7 +1,3 @@
 BLOB_COUNT=$(git cat-file --batch-check='%(objectname) %(objecttype)' --batch-all-objects | grep blob | wc -l)
 
-if [ "$BLOB_COUNT" -gt 2 ]; then
-    exit 0
-else
-    exit 1
-fi
+test "$BLOB_COUNT" -gt 2
diff --git a/levels/02-tree/win b/levels/02-tree/win
new file mode 100644
index 0000000..40bc605
--- /dev/null
+++ b/levels/02-tree/win
@@ -0,0 +1 @@
+git cat-file -p c099013035060f20e8d8f5db69e158213fbec519
diff --git a/levels/03-commit/win b/levels/03-commit/win
new file mode 100644
index 0000000..4bd1a81
--- /dev/null
+++ b/levels/03-commit/win
@@ -0,0 +1,3 @@
+COMMIT_COUNT=$(git cat-file --batch-check='%(objectname) %(objecttype)' --batch-all-objects | grep commit | wc -l)
+
+test "$COMMIT_COUNT" -gt 0
diff --git a/levels/04-parents/win b/levels/04-parents/win
new file mode 100644
index 0000000..ce20826
--- /dev/null
+++ b/levels/04-parents/win
@@ -0,0 +1,10 @@
+COMMITS=$(git cat-file --batch-check='%(objectname) %(objecttype)' --batch-all-objects | grep commit | cut -f1 -d" ")
+
+for COMMIT in $COMMITS; do
+    echo a commit named $COMMIT
+    if [ $(git rev-list $COMMIT | wc -l) -ge 3 ]; then
+        exit 0
+    fi
+done
+
+exit 1
diff --git a/main.gd b/main.gd
index e74486d..b69685f 100644
--- a/main.gd
+++ b/main.gd
@@ -85,7 +85,7 @@ func load_level(id):
 	dir.copy(win_script, win_script_target)
 
 func load_next_level():
-	current_level += 1
+	current_level = (current_level + 1) % list_levels().size()
 	load_level(current_level)
 	
 func construct_repo(script, path):
diff --git a/repository.tscn b/repository.tscn
index cdc849d..5cf7bb7 100644
--- a/repository.tscn
+++ b/repository.tscn
@@ -18,7 +18,6 @@ __meta__ = {
 }
 
 [node name="Index" type="Label" parent="."]
-visible = false
 margin_left = 32.0
 margin_top = 80.0
 margin_right = 375.079
@@ -31,7 +30,6 @@ __meta__ = {
 }
 
 [node name="IndexLabel" type="Label" parent="."]
-visible = false
 margin_left = 21.0
 margin_top = 65.0
 margin_right = 377.0
diff --git a/shell.gd b/shell.gd
index 0e2cd9b..cb636d2 100644
--- a/shell.gd
+++ b/shell.gd
@@ -32,6 +32,22 @@ func run(command):
 	hacky_command += "cd '%s';" % _cwd
 	hacky_command += command
 	
+	# Godot's OS.execute wraps each argument in double quotes before executing.
+	# Because we want to be in a single-quote context, where nothing is evaluated,
+	# we end those double quotes and start a single quoted string. For each single
+	# quote appearing in our string, we close the single quoted string, and add
+	# a double quoted string containing the single quote. Ooooof!
+	#
+	# Example: The string
+	# 
+	#     test 'fu' "bla" blubb
+	# 
+	# becomes
+	# 
+	#     "'test '"'"'fu'"'"' "bla" blubb
+	# 
+	hacky_command = '"\''+hacky_command.replace("'", "'\"'\"'")+'\'"'
+	
 	var output = game.exec(_shell_binary(), ["-c",  hacky_command])
 	
 	if debug:
diff --git a/terminal.gd b/terminal.gd
index 7e0ad18..6229f47 100644
--- a/terminal.gd
+++ b/terminal.gd
@@ -49,7 +49,7 @@ func run_command_in_a_thread(command):
 	check_win_condition()
 	
 	input.text = ""
-	input.editable = true	
+	input.editable = true
 	output.text = output.text + "$ " + command + "\n" + o
 	repo.update_everything() 
 
@@ -57,5 +57,5 @@ func receive_output(text):
 	output.text += text
 	
 func check_win_condition():
-	if repo.shell.run("bash /tmp/win && echo yes || echo no") == "yes\n":
+	if repo.shell.run("bash /tmp/win &>/dev/null && echo yes || echo no") == "yes\n":
 		main.load_next_level()
diff --git a/terminal.tscn b/terminal.tscn
index b8a03b1..bbfde72 100644
--- a/terminal.tscn
+++ b/terminal.tscn
@@ -11,14 +11,14 @@ content_margin_top = 10.0
 content_margin_bottom = 10.0
 bg_color = Color( 0, 0, 0, 1 )
 
-[sub_resource type="StyleBoxFlat" id=3]
+[sub_resource type="StyleBoxFlat" id=2]
 content_margin_left = 10.0
 content_margin_right = 10.0
 content_margin_top = 10.0
 content_margin_bottom = 5.0
 bg_color = Color( 0.0862745, 0.0862745, 0.0862745, 1 )
 
-[sub_resource type="StyleBoxFlat" id=2]
+[sub_resource type="StyleBoxFlat" id=3]
 content_margin_left = 10.0
 content_margin_right = 10.0
 content_margin_top = 10.0
@@ -43,7 +43,7 @@ __meta__ = {
 
 [node name="Output" type="RichTextLabel" parent="Control"]
 margin_right = 1920.0
-margin_bottom = 999.0
+margin_bottom = 979.0
 size_flags_vertical = 3
 custom_styles/normal = SubResource( 1 )
 custom_fonts/normal_font = ExtResource( 1 )
@@ -51,18 +51,26 @@ scroll_following = true
 
 [node name="Button" parent="Control" instance=ExtResource( 4 )]
 margin_left = 0.0
-margin_top = 999.0
+margin_top = 979.0
 margin_right = 1920.0
-margin_bottom = 1019.0
+margin_bottom = 999.0
 text = "git commit --allow-empty"
 align = 0
 
 [node name="Button5" parent="Control" instance=ExtResource( 4 )]
 margin_left = 0.0
+margin_top = 999.0
+margin_right = 1920.0
+margin_bottom = 1019.0
+text = "echo $RANDOM | git hash-object -w --stdin"
+align = 0
+
+[node name="Button6" parent="Control" instance=ExtResource( 4 )]
+margin_left = 0.0
 margin_top = 1019.0
 margin_right = 1920.0
 margin_bottom = 1039.0
-text = "echo $RANDOM | git hash-object -w --stdin"
+text = "git update-index --add noises; git write-tree"
 align = 0
 
 [node name="Button2" parent="Control" instance=ExtResource( 4 )]
@@ -96,8 +104,8 @@ align = 0
 margin_top = 1039.0
 margin_right = 1920.0
 margin_bottom = 1080.0
-custom_styles/read_only = SubResource( 3 )
-custom_styles/normal = SubResource( 2 )
+custom_styles/read_only = SubResource( 2 )
+custom_styles/normal = SubResource( 3 )
 custom_fonts/font = ExtResource( 1 )
 caret_blink = true
 __meta__ = {