diff --git a/.github/workflows/test_builds.yaml b/.github/workflows/test_builds.yaml
index 10f1febad..a7ad6f47e 100644
--- a/.github/workflows/test_builds.yaml
+++ b/.github/workflows/test_builds.yaml
@@ -13,6 +13,10 @@ jobs:
     runs-on: ubuntu-latest
     container:
       image: ubuntu:26.04
+      options: >-
+        --cap-add SYS_ADMIN
+        --device /dev/fuse
+        --security-opt apparmor:unconfined
     steps:
       - name: Update Ubuntu
         run: |
@@ -51,6 +55,10 @@ jobs:
     runs-on: ubuntu-latest
     container:
       image: fedora:latest
+      options: >-
+        --cap-add SYS_ADMIN
+        --device /dev/fuse
+        --security-opt apparmor:unconfined
     steps:
       - name: Update Fedora
         run: |
@@ -89,6 +97,10 @@ jobs:
     runs-on: ubuntu-latest
     container:
       image: archlinux:latest
+      options: >-
+        --cap-add SYS_ADMIN
+        --device /dev/fuse
+        --security-opt apparmor:unconfined
     steps:
       - name: Update Arch
         run: |
diff --git a/GNUmakefile b/GNUmakefile
index 843f4edce..eb191d30d 100755
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -108,6 +108,7 @@ else
     endif
 
     ifeq ($(COMPILER_TYPE),gcc)
+        ADDITIONAL_OBJCFLAGS     += -std=gnu99
         ADDITIONAL_LDFLAGS       += -fuse-ld=bfd
     else
         ADDITIONAL_LDFLAGS       += -fuse-ld=lld
diff --git a/ShellScripts/Linux/install_freedesktop_fn.sh b/ShellScripts/Linux/install_freedesktop_fn.sh
index 7638b3bfc..72519c493 100644
--- a/ShellScripts/Linux/install_freedesktop_fn.sh
+++ b/ShellScripts/Linux/install_freedesktop_fn.sh
@@ -35,7 +35,6 @@ install_freedesktop() {
         install -D "$PROGDIR/oolite.debug" "$1/$2/oolite.debug" || { echo "$err_msg install oolite debug symbols" >&2; return 1; }
     fi
     install -D "$PROGDIR/run_oolite.sh" "$APPBIN/run_oolite.sh" || { echo "$err_msg install run_oolite.sh" >&2; return 1; }
-    install -D "$PROGDIR/splash-launcher" "$APPBIN/splash-launcher" || { echo "$err_msg install splash-launcher" >&2; return 1; }
 
     # Resources copy
     mkdir -p "$APPBIN/Resources"
diff --git a/ShellScripts/Linux/install_package_fn.sh b/ShellScripts/Linux/install_package_fn.sh
index 9ce2cdb62..fb2830131 100644
--- a/ShellScripts/Linux/install_package_fn.sh
+++ b/ShellScripts/Linux/install_package_fn.sh
@@ -130,9 +130,9 @@ install_package() {
 
         "appimage")
             case "$CURRENT_DISTRO" in
-                debian) PKG_NAME="NONE" ;;
-                redhat) PKG_NAME="desktop-file-utils which zsync" ;;
-                arch) PKG_NAME="desktop-file-utils zsync" ;;
+                debian) PKG_NAME="file fuse3" ;;
+                redhat) PKG_NAME="file fuse3 desktop-file-utils which zsync" ;;
+                arch) PKG_NAME="file fuse3 desktop-file-utils zsync" ;;
             esac ;;
 
         "flatpak") PKG_NAME="flatpak flatpak-builder" ;;
diff --git a/ShellScripts/Linux/run_oolite.sh b/ShellScripts/Linux/run_oolite.sh
index f61574a28..8ced6fe2d 100755
--- a/ShellScripts/Linux/run_oolite.sh
+++ b/ShellScripts/Linux/run_oolite.sh
@@ -4,13 +4,9 @@
 HERE="$(dirname "$(readlink -f "$0")")"
 
 DEBUG=false
-SHOW_SPLASH=true
 # Loop through all arguments
 for arg in "$@"; do
   case "$arg" in
-    -nosplash|--nosplash|-help|--help)
-      SHOW_SPLASH=false
-      ;;
     debug)
       DEBUG=true
       shift
@@ -55,13 +51,7 @@ launch_guarded() {
     if [[ "$DEBUG" == true ]]; then
         exec gdb --args "$OO_EXEDIR/oolite" "$@" -nosplash
     fi
-    if [[ "$SHOW_SPLASH" == true ]]; then
-        "$OO_EXEDIR/splash-launcher" "$OO_EXEDIR/Resources/Images/splash.bmp" &
-        "$OO_EXEDIR/oolite" "$@" -nosplash
-    else
-        # already has -nosplash
-        "$OO_EXEDIR/oolite" "$@"
-    fi
+    "$OO_EXEDIR/oolite" "$@"
     local EXIT_CODE=$?
 
     if [ $EXIT_CODE -eq 0 ]; then
diff --git a/installers/appimage/create_appimage.sh b/installers/appimage/create_appimage.sh
index dbdaf1880..e6305730e 100755
--- a/installers/appimage/create_appimage.sh
+++ b/installers/appimage/create_appimage.sh
@@ -59,6 +59,9 @@ run_script() {
     export DEPLOY_VULKAN
     local DEPLOY_LOCALE=0
     export DEPLOY_LOCALE
+    local STRACE_MODE=0
+    export STRACE_MODE
+
     # install_metadatainfo_fn already put the files in the parameters below in the right place,
     # but no harm putting again here
     if ! $SHARUN_BIN "$APPBIN/oolite"; then
@@ -82,8 +85,15 @@ run_script() {
         return 1
     fi
 
+    APPIMAGETOOL_BIN="./appimagetool"
+    if [ ! -x "$APPIMAGETOOL_BIN" ]; then
+        echo "📥 appimagetool not found. Downloading..."
+        curl -o "$APPIMAGETOOL_BIN" -L https://github.com/AppImage/appimagetool/releases/download/continuous/appimagetool-$ARCH.AppImage || { echo "❌ appimagetool download failed" >&2; exit 1; }
+        chmod +x "$APPIMAGETOOL_BIN"
+    fi
+
     echo "Creating AppImage $OUTNAME..."
-    if ! $SHARUN_BIN --make-appimage; then
+    if ! $APPIMAGETOOL_BIN "$ABS_APPDIR" "$OUTNAME"; then
         echo "❌ AppImage creation failed!" >&2
         return 1
     fi
diff --git a/installers/flatpak/create_flatpak.sh b/installers/flatpak/create_flatpak.sh
index f22f7f804..94fed54d5 100755
--- a/installers/flatpak/create_flatpak.sh
+++ b/installers/flatpak/create_flatpak.sh
@@ -32,21 +32,35 @@ run_script() {
     fi
 
     # check manifest
+    LINT_EXCEPTIONS=$(mktemp /tmp/oolite-lint-XXXXXX.json)
+    cat <<EOF > "$LINT_EXCEPTIONS"
+{
+  "space.oolite.Oolite": [
+    "finish-args-has-dev-input"
+  ]
+}
+EOF
+    trap 'rm -f "$LINT_EXCEPTIONS"' RETURN EXIT
+
     if command -v flatpak-builder-lint >/dev/null 2>&1; then
-        if ! flatpak-builder-lint manifest "$MANIFEST"; then
+        if ! flatpak-builder-lint manifest "$MANIFEST" --exceptions --user-exceptions="$LINT_EXCEPTIONS"; then
             echo "❌ Flatpak manifest lint failed!" >&2
-            cat $MANIFEST
+            cat "$MANIFEST"
             echo "❌ Flatpak manifest lint failed!" >&2
             return 1
         fi
     else
         echo "Native linter not found. Falling back to Flatpak container..."
-        if ! flatpak run --command=flatpak-builder-lint org.flatpak.Builder manifest "$MANIFEST"; then
+        if ! flatpak run --filesystem="$LINT_EXCEPTIONS" --command=flatpak-builder-lint org.flatpak.Builder manifest "$MANIFEST" --exceptions --user-exceptions="$LINT_EXCEPTIONS"; then
             echo "❌ Flatpak manifest lint failed!" >&2
             return 1
         fi
     fi
 
+    # 3. Clean up
+    rm -f "$LINT_EXCEPTIONS"
+    trap - RETURN EXIT
+
     echo "Creating Flatpak..."
     if ! flatpak remote-add \
       --user \
diff --git a/installers/flatpak/space.oolite.Oolite.yaml b/installers/flatpak/space.oolite.Oolite.yaml
index 9ae68c5da..33456d2ff 100644
--- a/installers/flatpak/space.oolite.Oolite.yaml
+++ b/installers/flatpak/space.oolite.Oolite.yaml
@@ -9,12 +9,14 @@ build-options:
   prepend-ld-library-path: /usr/lib/sdk/llvm22/lib
 command: run_oolite.sh
 finish-args:
+  - --require-version=1.16.0
   - --socket=wayland
   - --socket=fallback-x11
   - --share=ipc
   - --share=network
   - --socket=pulseaudio
   - --device=dri
+  - --device=input
 cleanup:
   - /include
   - /lib/pkgconfig
diff --git a/src/SDL/MyOpenGLView.m b/src/SDL/MyOpenGLView.m
index 54c7eaf72..925664a8a 100644
--- a/src/SDL/MyOpenGLView.m
+++ b/src/SDL/MyOpenGLView.m
@@ -192,8 +192,20 @@ - (void) createWindowWithSize: (NSSize) size
 	}
 
 	NSString *windowCaption = [self getWindowCaption];
-	int windowFlags = SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_HIGH_PIXEL_DENSITY;
-	window = SDL_CreateWindow([windowCaption UTF8String], size.width, size.height, windowFlags);
+	Uint32 windowFlags = SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_HIGH_PIXEL_DENSITY;
+
+	// Define modern SDL3 properties for window configuration
+	SDL_PropertiesID props = SDL_CreateProperties();
+	SDL_SetStringProperty(props, SDL_PROP_WINDOW_CREATE_TITLE_STRING, [windowCaption UTF8String]);
+	SDL_SetNumberProperty(props, SDL_PROP_WINDOW_CREATE_WIDTH_NUMBER, size.width);
+	SDL_SetNumberProperty(props, SDL_PROP_WINDOW_CREATE_HEIGHT_NUMBER, size.height);
+	SDL_SetNumberProperty(props, SDL_PROP_WINDOW_CREATE_FLAGS_NUMBER, windowFlags);
+
+	// Explicit centering properties setup for SDL3
+	SDL_SetNumberProperty(props, SDL_PROP_WINDOW_CREATE_X_NUMBER, SDL_WINDOWPOS_CENTERED);
+	SDL_SetNumberProperty(props, SDL_PROP_WINDOW_CREATE_Y_NUMBER, SDL_WINDOWPOS_CENTERED);
+
+	window = SDL_CreateWindowWithProperties(props);
 	if (!window)
 	{
 		OOLog(@"display.initGL", @"%@", @"Trying 8-bpcc, 24-bit depth buffer");
@@ -203,7 +215,7 @@ - (void) createWindowWithSize: (NSSize) size
 		SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
 		SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
 		SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
-		window = SDL_CreateWindow([windowCaption UTF8String], size.width, size.height, windowFlags);
+		window = SDL_CreateWindowWithProperties(props);
 		_hdrOutput = NO;
 	}
 
@@ -217,9 +229,12 @@ - (void) createWindowWithSize: (NSSize) size
 		// and if it's this bad, forget even trying to multisample!
 		SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 0);
 		SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, 0);
-		window = SDL_CreateWindow([windowCaption UTF8String], size.width, size.height, windowFlags);
+		window = SDL_CreateWindowWithProperties(props);
 	}
 
+	// Clean up properties block
+	SDL_DestroyProperties(props);
+
 	if (!window)
 	{
 		const char * errStr = SDL_GetError();
@@ -248,7 +263,7 @@ - (void) createWindowWithSize: (NSSize) size
 		OOLog(@"sdl.window_handle", @"%@", @"Failed to retrieve window handle");
 		exit(1);
 	}
-	
+
 	// This must be inited after windowHandle has been set - we need the main window handle in order to get monitor info
 	if (![self getCurrentMonitorInfo:&monitorInfo])
 	{
@@ -256,7 +271,7 @@ - (void) createWindowWithSize: (NSSize) size
 	}
 
 	atDesktopResolution = YES;
-	
+
 #if USE_UNDOCUMENTED_DARKMODE_API
 	// dark mode stuff - this is mainly for the winodw titlebar's context menu
 	HMODULE hUxTheme = LoadLibraryExW(L"uxtheme.dll", NULL, LOAD_LIBRARY_SEARCH_SYSTEM32);
@@ -285,18 +300,18 @@ - (void) createWindowWithSize: (NSSize) size
 	SDL_DestroySurface(icon);
 
 	_colorSaturation = 1.0f;
-	
+
 #if OOLITE_WINDOWS
 	_hdrMaxBrightness = [prefs oo_floatForKey:@"hdr-max-brightness" defaultValue:1000.0f];
 	_hdrPaperWhiteBrightness = [prefs oo_floatForKey:@"hdr-paperwhite-brightness" defaultValue:200.0f];
 	_hdrToneMapper = OOHDRToneMapperFromString([prefs oo_stringForKey:@"hdr-tone-mapper" defaultValue:@"OOHDR_TONEMAPPER_ACES_APPROX"]);
 #endif
-	
+
 	_sdrToneMapper = OOSDRToneMapperFromString([prefs oo_stringForKey:@"sdr-tone-mapper" defaultValue:@"OOSDR_TONEMAPPER_ACES"]);
-	
+
 	SDL_SetWindowSurfaceVSync(window, vSyncPreference);
 	OOLog(@"display.initGL", @"V-Sync %@requested.", vSyncPreference ? @"" : @"not ");
-	
+
 	int testAttrib = -1;
 	OOLog(@"display.initGL", @"%@", @"Achieved color / depth buffer sizes (bits):");
 	SDL_GL_GetAttribute(SDL_GL_RED_SIZE, &testAttrib);
@@ -316,9 +331,9 @@ - (void) createWindowWithSize: (NSSize) size
 #if OOLITE_WINDOWS
   	OOLog(@"display.initGL", @"Pixel format index: %d", GetPixelFormat(GetDC(windowHandle)));
 #endif
-	
+
 	// Verify V-sync successfully set - report it if not
-	
+
 	int hasVsync;
 	if (vSyncPreference && (!SDL_GetWindowSurfaceVSync(window, &hasVsync) || !hasVsync))
 	{
@@ -376,10 +391,10 @@ - (id) init
 		{
 			showSplashScreen = YES;
 		}
-		
+
 		// if V-sync is disabled at the command line, override the defaults file
 		if ([arg isEqual:@"-novsync"] || [arg isEqual:@"--novsync"])  vSyncPreference = NO;
-		
+
 		if ([arg isEqual: @"-hdr"])  bitsPerColorComponent = 16;
 
   		// build the startup command string so that we can log it
@@ -401,7 +416,6 @@ - (id) init
 	}
 
 	[self populateFullScreenModelist];
-	SDL_SetEnvironmentVariable(SDL_GetEnvironment(), "SDL_VIDEO_WINDOW_POS", "center", YES);
 
 	// Find what the full screen and windowed settings are.
 	fullScreen = NO;
@@ -440,7 +454,7 @@ - (id) init
 
 	virtualJoystickPosition = NSMakePoint(0.0,0.0);
 	mouseWarped = NO;
-	
+
 	_mouseVirtualStickSensitivityFactor = OOClamp_0_1_f([prefs oo_floatForKey:@"mouse-flight-sensitivity" defaultValue:0.95f]);
 	// ensure no chance of a divide by zero later on
 	if (_mouseVirtualStickSensitivityFactor < 0.005f)  _mouseVirtualStickSensitivityFactor = 0.005f;
@@ -450,7 +464,7 @@ - (id) init
 	isAlphabetKeyDown = NO;
 
 	timeIntervalAtLastClick = timeSinceLastMouseWheel = [NSDate timeIntervalSinceReferenceDate];
-	
+
 	_mouseWheelDelta = 0.0f;
 
 	m_glContextInitialized = NO;
@@ -482,8 +496,10 @@ - (void) endSplashScreen
 #else
 	if (!showSplashScreen)  return;
 
+	SDL_HideWindow(window);
 	SDL_SetWindowSize(window, firstScreen.width, firstScreen.height);
 	SDL_SetWindowFullscreen(window, fullScreen);
+	SDL_ShowWindow(window);
 
 	/* MKW 2011.11.11
 	 * Eat all SDL events to gobble up any resize events while the