diff --git a/README.md b/README.md
index 43183f1..f370412 100644
--- a/README.md
+++ b/README.md
@@ -105,8 +105,15 @@ rpm-ostree rebase ostree-unverified-registry:YOUR-FORGEJO-DOMAIN/YOUR-USERNAME/k
 
 ## Customizing KAMOS
 
-- **Add packages baked into the OS:** edit `build_files/build.sh`
-  (`dnf5 -y install <package>`), push — CI rebuilds the image.
+- **Add/remove system packages:** edit [`build_files/packages.list`](build_files/packages.list)
+  — one package name per line, `#` for comments. Push, CI rebuilds.
+- **Add/remove default apps (Flatpaks):** edit
+  [`system_files/usr/share/kamos/flatpaks.list`](system_files/usr/share/kamos/flatpaks.list)
+  with Flathub app IDs — installed automatically on each machine's first boot.
+- **Wallpaper/logo:** replace
+  `system_files/usr/share/backgrounds/kamos/kamos-default.png` and
+  `system_files/usr/share/pixmaps/kamos-logo.png`. The build stamps the
+  wallpaper over all stock desktop wallpapers.
 - **Add config files:** drop them under `system_files/` mirroring the target
   path (e.g. `system_files/etc/foo.conf` → `/etc/foo.conf`).
 - **Apps like Heroic, Lutris, Discord, OBS:** install as Flatpaks after boot
diff --git a/build_files/build.sh b/build_files/build.sh
index 33a915a..09bd508 100644
--- a/build_files/build.sh
+++ b/build_files/build.sh
@@ -11,23 +11,37 @@ sed -i 's/^NAME=.*/NAME="KAMOS"/' /usr/lib/os-release
 sed -i 's/^PRETTY_NAME=.*/PRETTY_NAME="KAMOS (Gaming Edition)"/' /usr/lib/os-release
 
 ### ---------------------------------------------------------------
-### 2. Extra packages layered on top of Bazzite
-###    Bazzite stable already ships: Steam, Gamescope, Proton (via
-###    Steam), MangoHud, vkBasalt, gamemode, Lutris deps, Waydroid,
-###    Distrobox, KDE Plasma, HDR/VRR support, fsync kernel.
-###    Add anything extra you want baked into the OS here.
+### 2. System packages from build_files/packages.list
 ### ---------------------------------------------------------------
-dnf5 -y install \
-    btop \
-    fastfetch
-
-# Examples (uncomment to include):
-# dnf5 -y install openrgb            # RGB peripheral control
-# dnf5 -y install corectrl           # AMD GPU/CPU tuning UI
-# dnf5 -y install input-remapper     # remap controller/keyboard
+PKGS=$(sed -e 's/#.*//' -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//' \
+    /tmp/build_files/packages.list | grep -v '^$' || true)
+if [ -n "$PKGS" ]; then
+    # shellcheck disable=SC2086
+    dnf5 -y install $PKGS
+fi
 
 ### ---------------------------------------------------------------
-### 3. System defaults
+### 3. Wallpaper branding: replace every stock wallpaper image with
+###    the KAMOS one so the desktop defaults to KAMOS artwork
+### ---------------------------------------------------------------
+WALL=/usr/share/backgrounds/kamos/kamos-default.png
+if [ -f "$WALL" ]; then
+    find /usr/share/wallpapers /usr/share/backgrounds \
+        -type f \( -name '*.png' -o -name '*.jpg' -o -name '*.jpeg' \) \
+        ! -path '*/kamos/*' -print0 2>/dev/null |
+    while IFS= read -r -d '' img; do
+        cp -f "$WALL" "$img"
+    done
+fi
+
+### ---------------------------------------------------------------
+### 4. First-boot Flatpak apps (list: /usr/share/kamos/flatpaks.list)
+### ---------------------------------------------------------------
+chmod +x /usr/libexec/kamos-install-flatpaks
+systemctl enable kamos-flatpaks.service
+
+### ---------------------------------------------------------------
+### 5. System defaults
 ### ---------------------------------------------------------------
 # Enable weekly automatic OS updates (staged, applied on reboot)
 systemctl enable rpm-ostreed-automatic.timer || true
diff --git a/build_files/packages.list b/build_files/packages.list
new file mode 100644
index 0000000..94fa93c
--- /dev/null
+++ b/build_files/packages.list
@@ -0,0 +1,11 @@
+# System packages baked into the KAMOS image (one per line).
+# Add a package name to include it in the OS; delete a line to remove it.
+# Lines starting with # are ignored. Changes take effect on the next build.
+
+btop
+fastfetch
+
+# --- popular extras (remove the # to enable) ---
+# openrgb            # RGB peripheral control
+# corectrl           # AMD GPU/CPU tuning UI
+# input-remapper     # remap controller/keyboard buttons
diff --git a/system_files/usr/lib/systemd/system/kamos-flatpaks.service b/system_files/usr/lib/systemd/system/kamos-flatpaks.service
new file mode 100644
index 0000000..28bb1a7
--- /dev/null
+++ b/system_files/usr/lib/systemd/system/kamos-flatpaks.service
@@ -0,0 +1,13 @@
+[Unit]
+Description=Install KAMOS default Flatpak apps (first boot)
+Wants=network-online.target
+After=network-online.target
+ConditionPathExists=!/var/lib/kamos-flatpaks-done
+
+[Service]
+Type=oneshot
+ExecStart=/usr/libexec/kamos-install-flatpaks
+RemainAfterExit=yes
+
+[Install]
+WantedBy=multi-user.target
diff --git a/system_files/usr/libexec/kamos-install-flatpaks b/system_files/usr/libexec/kamos-install-flatpaks
new file mode 100644
index 0000000..0f3feb6
--- /dev/null
+++ b/system_files/usr/libexec/kamos-install-flatpaks
@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+# Installs the default KAMOS Flatpak apps on first boot (runs once).
+set -u
+
+LIST=/usr/share/kamos/flatpaks.list
+STAMP=/var/lib/kamos-flatpaks-done
+
+[ -f "$STAMP" ] && exit 0
+
+flatpak remote-add --if-not-exists --system flathub \
+    https://dl.flathub.org/repo/flathub.flatpakrepo || true
+
+ok=1
+while IFS= read -r app; do
+    case "$app" in ''|\#*) continue ;; esac
+    app="${app%%#*}"; app="$(echo "$app" | xargs)"
+    [ -z "$app" ] && continue
+    flatpak install --system --noninteractive --or-update flathub "$app" || ok=0
+done < "$LIST"
+
+# Only mark done when everything succeeded, so it retries next boot otherwise
+[ "$ok" = 1 ] && touch "$STAMP"
+exit 0
diff --git a/system_files/usr/share/backgrounds/kamos/kamos-default.png b/system_files/usr/share/backgrounds/kamos/kamos-default.png
new file mode 100644
index 0000000..7b4db0d
Binary files /dev/null and b/system_files/usr/share/backgrounds/kamos/kamos-default.png differ
diff --git a/system_files/usr/share/kamos/flatpaks.list b/system_files/usr/share/kamos/flatpaks.list
new file mode 100644
index 0000000..ad119cb
--- /dev/null
+++ b/system_files/usr/share/kamos/flatpaks.list
@@ -0,0 +1,13 @@
+# Flatpak apps KAMOS installs automatically on first boot (one per line).
+# Add a Flathub app ID to include it; delete a line to remove it from new
+# installs. Find IDs at https://flathub.org (page URL ends with the ID).
+# Lines starting with # are ignored.
+
+com.heroicgameslauncher.hgl
+net.davidotek.pupgui2
+
+# --- popular extras (remove the # to enable) ---
+# com.discordapp.Discord
+# com.obsproject.Studio
+# org.videolan.VLC
+# com.spotify.Client
diff --git a/system_files/usr/share/pixmaps/kamos-logo.png b/system_files/usr/share/pixmaps/kamos-logo.png
new file mode 100644
index 0000000..08341bf
Binary files /dev/null and b/system_files/usr/share/pixmaps/kamos-logo.png differ