diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5959270..66a1f58 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ one per merged pull request.
 ## 2.11.0 - 2026-10-01
 
 - `5da1833` **feat: "Start Steam silently" sub-option: under the SteamOS conversion (`silent`, opt-in now: it was always on before; an existing one is moved from its systemd unit to the autostart entry by the "update") and under Gaming on NVIDIA (`nvsilent`, opt-in, not together with Big Picture); the SteamOS one is called "Start Steam silently in desktop mode" and is always shown, also on a Steam Machine; it is Steam's own autostart entry (`~/.config/autostart/steam.desktop`), so Steam's setting "Run Steam when my computer starts" follows it**
+- **feat: `STEAMIFY_NO_DOWNLOAD` (the ISO's `steamify.nodownload` kernel parameter): the installed system's first login runs the Steamify bundle of the ISO instead of downloading the newest release (to test an unreleased Steamify)**
 - **fix: the SteamOS theme no longer leaves a blank Discover pin in the taskbar (Plasma's default taskbar pins Discover, which CachyOS doesn't install); the taskbar gets CachyOS's own pins (System Settings, files, browser), also on the ISO's first login**
 - **feat: "Steam Deck/Machine icons" (`glyphs`) is a sub-option of the SteamOS conversion, like "Start Steam silently in desktop mode": it only changes gaming mode**
 
diff --git a/lib/first-login.sh b/lib/first-login.sh
index 47eb9d3..a6f1c7b 100644
--- a/lib/first-login.sh
+++ b/lib/first-login.sh
@@ -7,13 +7,24 @@
 
 FIRST_LOGIN_ENTRY="${XDG_CONFIG_HOME:-$HOME/.config}/autostart/steamify-first-login.desktop"
 FIRST_LOGIN_SCRIPT="$STEAMIFY_BIN/first-login"
+FIRST_LOGIN_BUNDLE="$STEAMIFY_BIN/first-login-steamify.sh"
 
 first_login_schedule() {
+    # The newest release's Steamify runs at the first login. STEAMIFY_NO_DOWNLOAD (the ISO was started with
+    # steamify.nodownload, to test an unreleased Steamify): this very bundle runs instead.
+    local run
+    if [[ -n "${STEAMIFY_NO_DOWNLOAD:-}" && -f "$SCRIPT_DIR/steamify.sh" && ! -d "$SCRIPT_DIR/lib" ]]; then
+        install_executable "$FIRST_LOGIN_BUNDLE" 755 < "$SCRIPT_DIR/steamify.sh"
+        run="bash \"$FIRST_LOGIN_BUNDLE\" --first-login; rm -f \"$FIRST_LOGIN_BUNDLE\""
+    else
+        run="curl -fsSL --max-time 30 \"$WIZARD_URL\" | bash -s -- --first-login"
+    fi
     install_executable "$FIRST_LOGIN_SCRIPT" 755 << EOF2
 #!/bin/bash
 # Installed by Steamify CachyOS: runs once, at the first desktop login.
 set -o pipefail
-curl -fsSL --max-time 30 "$WIZARD_URL" | bash -s -- --first-login
+mkdir -p ~/.cache
+{ $run; } > ~/.cache/steamify-first-login.log 2>&1
 rm -f "$FIRST_LOGIN_ENTRY" "\$0"
 [[ -x "$WIZARD_APP_LAUNCHER" ]] && exec "$WIZARD_APP_LAUNCHER"
 EOF2