--- a/meson.build
+++ b/meson.build
@@ -227,6 +227,10 @@
 fftw_dep = dependency('fftw3f', static: is_static)
 threads_dep = dependency('threads')
 if host_platform == 'emscripten'
+	# fredygames: built without pthreads (no SharedArrayBuffer / cross-origin isolation on the host page)
+	threads_dep = []
+endif
+if host_platform == 'emscripten'
 	app_exe_jssafe = app_exe.underscorify()
 	png_dep = []
 	sdl2_dep = []
@@ -241,17 +245,13 @@
 		'-s', 'FS_DEBUG',
 		'-s', 'MODULARIZE',
 		'-s', 'EXPORT_NAME=create_' + app_exe_jssafe,
-		'-Wl,-u,_emscripten_run_callback_on_thread',
 		'-lidbfs.js',
-		'--source-map-base=./',
 	]
 	emcc_args = [
 		'-s', 'USE_SDL=2',
 		'-s', 'USE_BZIP2=1',
 		'-s', 'USE_LIBPNG',
-		'-s', 'USE_PTHREADS',
 		'-s', 'DISABLE_EXCEPTION_CATCHING=0',
-		'-gsource-map',
 	]
 	project_link_args += emcc_args
 	project_cpp_args += emcc_args
--- a/src/common/platform/Emscripten.cpp
+++ b/src/common/platform/Emscripten.cpp
@@ -17,9 +17,8 @@
 {
 void OpenURI(ByteString uri)
 {
-	EM_ASM({
-		open(UTF8ToString($0));
-	}, uri.c_str());
+	// fredygames: links to the official site, forum and wiki are not opened from the game
+	(void)uri;
 }
 
 void DoRestart()
--- a/src/gui/game/GameController.cpp
+++ b/src/gui/game/GameController.cpp
@@ -1780,6 +1780,9 @@
 
 bool GameController::ThreadedRenderingAllowed()
 {
+#if defined(__EMSCRIPTEN__) && !defined(__EMSCRIPTEN_PTHREADS__)
+	return false; // fredygames: no threads in this build
+#endif
 	return gameModel->GetThreadedRendering() && !GetPaused() && !commandInterface->HaveSimGraphicsEventHandlers();
 }
 
--- a/src/simulation/gravity/Fft.cpp
+++ b/src/simulation/gravity/Fft.cpp
@@ -11,6 +11,11 @@
 #include <mutex>
 #include <condition_variable>
 
+#if defined(__EMSCRIPTEN__) && !defined(__EMSCRIPTEN_PTHREADS__)
+// fredygames: no threads in this build, gravity is computed on the main thread when dispatched
+# define GRAVITY_NO_THREAD
+#endif
+
 // DFT is cyclic in nature; gravity would wrap around sort of like in loop mode without the 2x here;
 // in fact it still does, it's just not as visible. the arrays are 2x as big along all dimensions as normal cell maps
 constexpr auto blocks = CELLS * 2;
@@ -74,6 +79,10 @@
 
 void GravityImpl::Dispatch()
 {
+#ifdef GRAVITY_NO_THREAD
+	Work();
+	return;
+#endif
 	{
 		std::unique_lock lk(stateMx);
 		working = true;
@@ -88,7 +97,9 @@
 		shouldStop = true;
 	}
 	stateCv.notify_one();
+#ifndef GRAVITY_NO_THREAD
 	thr.join();
+#endif
 }
 
 void GravityImpl::Wait()
@@ -183,6 +194,9 @@
 	//clear padded gravmap
 	std::fill(massBig.get(), massBig.get() + blocks.X * blocks.Y, 0.f);
 
+#ifdef GRAVITY_NO_THREAD
+	return;
+#endif
 	thr = std::thread([this]() {
 		while (true)
 		{
--- a/src/tasks/Task.cpp
+++ b/src/tasks/Task.cpp
@@ -12,7 +12,12 @@
 void Task::Start()
 {
 	before();
+#if defined(__EMSCRIPTEN__) && !defined(__EMSCRIPTEN_PTHREADS__)
+	// fredygames: no threads in this build, the task runs to completion here and Poll() picks up the result
+	doWork_wrapper();
+#else
 	std::thread([this]() { doWork_wrapper(); }).detach();
+#endif
 }
 
 int Task::GetProgress()