The game will detect if it was not started sucessfully (up to the main menu)...

The game will detect if it was not started sucessfully (up to the main menu) last time it was run and automatically enable safe mode in this case

game/engines/default/engine/Game.lua

@@ -548,6 +548,7 @@ end
 
 --- Called when the game window is moved around
 function _M:onWindowMoved(x, y)
+	config.settings.window.pos = config.settings.window.pos or {}
 	config.settings.window.pos.x = x
 	config.settings.window.pos.y = y
 	self:saveSettings("window_pos", ("window.pos = {x=%d, y=%d}\n"):format(x, y))

game/engines/default/engine/init.lua

@@ -74,6 +74,11 @@ for i, file in ipairs(fs.list("/settings/")) do
 	end
 end
 
+if config.settings.force_safeboot then
+	util.removeForceSafeBoot()
+	core.display.forceSafeMode()
+end
+
 if core.display.safeMode() then
 	config.settings.aa_text = false
 	config.settings.fbo_active = false

game/engines/default/engine/utils.lua

@@ -1986,6 +1986,24 @@ function util.browserOpenUrl(url)
 	return false
 end
 
+--- Safeboot mode
+function util.setForceSafeBoot()
+	local restore = fs.getWritePath()
+	fs.setWritePath(engine.homepath)
+	local f = fs.open("/settings/force_safeboot.cfg", "w")
+	if f then
+		f:write("force_safeboot = true\n")
+		f:close()
+	end
+	if restore then fs.setWritePath(restore) end
+end
+function util.removeForceSafeBoot()
+	local restore = fs.getWritePath()
+	fs.setWritePath(engine.homepath)
+	fs.delete("/settings/force_safeboot.cfg")
+	if restore then fs.setWritePath(restore) end
+end
+
 -- Ultra weird, this is used by the C serialization code because I'm too dumb to make lua_dump() work on windows ...
 function __dump_fct(f)
 	return string.format("%q", string.dump(f))

game/engines/default/modules/boot/class/Game.lua

@@ -167,6 +167,17 @@ For the same reason the save per level option should not be used unless you have
 	end
 
 	self:grabAddons()
+
+	-- We are running fine, remove the flag so that if we crash we will not restart into safe mode
+	util.removeForceSafeBoot()
+
+	if core.display.safeMode() then
+		Dialog:simpleLongPopup("Safe Mode", [[Oops! Either you activated safe mode manually or the game detected it did not start correctly last time and thus you are in #LIGHT_GREEN#safe mode#WHITE#.
+Safe Mode disabled all graphical options and sets a low FPS. It is not advisable to play this way (as it will be very painful and ugly).
+
+Please go to the Video Options and try enabling/disabling options and then restarting until you do not get this message.
+A usual problem is shaders and thus should be your first target to disable.]], 700)
+	end
 end
 
 function _M:grabAddons()

game/engines/default/modules/boot/load.lua

@@ -17,6 +17,9 @@
 -- Nicolas Casalini "DarkGod"
 -- darkgod@te4.org
 
+-- We are running, set a flag so that if we crash we will restart into safe mode
+util.setForceSafeBoot()
+
 -- This file loads the game module, and loads data
 local KeyBind = require "engine.KeyBind"
 local DamageType = require "engine.DamageType"

src/core_lua.c

@@ -2686,6 +2686,15 @@ static int is_safe_mode(lua_State *L)
 	return 1;
 }
 
+static int set_safe_mode(lua_State *L)
+{
+	safe_mode = TRUE;
+	fbo_active = FALSE;
+	shaders_active = FALSE;
+	multitexture_active = FALSE;
+	return 0;
+}
+
 static int sdl_get_modes_list(lua_State *L)
 {
 	SDL_PixelFormat format;
@@ -2954,6 +2963,7 @@ static const struct luaL_Reg displaylib[] =
 	{"drawQuadPart", gl_draw_quad_part},
 	{"FBOActive", gl_fbo_is_active},
 	{"safeMode", is_safe_mode},
+	{"forceSafeMode", set_safe_mode},
 	{"disableFBO", gl_fbo_disable},
 	{"drawStringNewSurface", sdl_surface_drawstring_newsurface},
 	{"drawStringBlendedNewSurface", sdl_surface_drawstring_newsurface_aa},