diff --git Makefile Makefile
index 16df332d5..73e5aa242 100644
--- Makefile
+++ Makefile
@@ -20,21 +20,22 @@ FREETYPE_CONFIG ?= freetype-config
 #FREETYPE_CONFIG ?= pkg-config freetype2
 
 BACKENDS      = allegro gdi sdl sdl2 mixer_sdl mixer_sdl2 posix
-COLOUR_DEPTHS = 0 16
 OSTYPES       = amiga beos freebsd haiku linux mingw mac openbsd
 
 ifeq ($(findstring $(BACKEND), $(BACKENDS)),)
   $(error Unkown BACKEND "$(BACKEND)", must be one of "$(BACKENDS)")
 endif
 
-ifeq ($(findstring $(COLOUR_DEPTH), $(COLOUR_DEPTHS)),)
-  $(error Unkown COLOUR_DEPTH "$(COLOUR_DEPTH)", must be one of "$(COLOUR_DEPTHS)")
-endif
-
 ifeq ($(findstring $(OSTYPE), $(OSTYPES)),)
   $(error Unkown OSTYPE "$(OSTYPE)", must be one of "$(OSTYPES)")
 endif
 
+ifeq ($(BACKEND),posix)
+  COLOUR_DEPTH = 0
+else
+  COLOUR_DEPTH = 16
+endif
+
 ifeq ($(OSTYPE),amiga)
   STD_LIBS ?= -lunix -lSDL_mixer -lsmpeg -lvorbisfile -lvorbis -logg
   CFLAGS   += -mcrt=newlib -DSIM_BIG_ENDIAN -gstabs+
@@ -83,14 +84,14 @@ LIBS += -lbz2 -lz
 ifdef OPTIMISE
   ifeq ($(shell expr $(OPTIMISE) \>= 1), 1)
     CFLAGS += -O3
-    ifeq ($(findstring $(OSTYPE), amiga),)
-      ifneq ($(findstring $(CXX), clang),)
+    ifeq ($(findstring amiga, $(OSTYPE)),)
+      ifneq ($(findstring clang, $(CXX)),)
         CFLAGS += -minline-all-stringops
       endif
     endif
   endif
 else
-  CFLAGS += -O
+  CFLAGS += -O2
 endif
 
 ifdef DEBUG
@@ -175,7 +176,11 @@ ifdef PROFILE
   ifeq ($(shell expr $(PROFILE) \>= 1), 1)
     CFLAGS   += -pg -DPROFILE
     ifeq ($(shell expr $(PROFILE) \>= 2), 1)
-      CFLAGS += -fno-inline -fno-schedule-insns
+      CFLAGS += -fno-inline
+
+      ifeq ($(findstring clang, $(CXX)),)
+        CFLAGS += -fno-schedule-insns
+      endif
     endif
     LDFLAGS  += -pg
   endif
@@ -698,14 +703,28 @@ PROGDIR  ?= $(BUILDDIR)
 PROG     ?= sim
 
 
+.DEFAULT_GOAL := all
+.PHONY: simutrans makeobj nettool
+
 include common.mk
 
 ifeq ($(OSTYPE),mac)
   include OSX/osx.mk
 endif
 
-
-.PHONY: makeobj
+all: simutrans makeobj nettool
 
 makeobj:
 	$(Q)$(MAKE) -e -C makeobj FLAGS="$(FLAGS)"
+
+nettool:
+	$(Q)$(MAKE) -e -C nettools FLAGS="$(FLAGS)"
+
+clean:
+	@echo "===> Cleaning up"
+	$(Q)rm -f $(OBJS)
+	$(Q)rm -f $(DEPS)
+	$(Q)rm -f $(PROGDIR)/$(PROG)
+	$(Q)rm -fr $(PROGDIR)/$(PROG).app
+	$(Q)$(MAKE) -e -C makeobj clean
+	$(Q)$(MAKE) -e -C nettools clean
diff --git common.mk common.mk
index 2921d6f22..04a6bed28 100644
--- common.mk
+++ common.mk
@@ -10,6 +10,8 @@ DIRS := $(sort $(dir $(OBJS)))
 # Make build directories
 DUMMY := $(shell mkdir -p $(DIRS))
 
+BUILDCONFIG_FILES := common.mk Makefile config.$(CFG)
+
 .PHONY: all clean
 
 .SUFFIXES: .rc
@@ -20,42 +22,35 @@ else
   Q =
 endif
 
-all: $(PROGDIR)/$(PROG)
+simutrans: $(PROGDIR)/$(PROG)
 
 $(PROGDIR)/$(PROG): $(OBJS)
 	@echo "===> LD  $@"
 	$(Q)$(HOSTCXX) $(OBJS) $(LDFLAGS) $(LIBS) -o $(PROGDIR)/$(PROG)
 
-clean:
-	@echo "===> Cleaning up"
-	$(Q)rm -f $(OBJS)
-	$(Q)rm -f $(DEPS)
-	$(Q)rm -f $(PROGDIR)/$(PROG)
-	$(Q)rm -fr $(PROGDIR)/$(PROG).app
-
 -include $(DEPS)
 
 # Silence stale header dependency errors
 %.h:
 	@true
 
-$(BUILDDIR)/%.o: %.mm
+$(BUILDDIR)/%.o: %.mm $(BUILDCONFIG_FILES)
 	@echo "===> Obj-c OSX $<"
 	$(Q)$(HOSTCXX) $(CXXFLAGS) $(OBJCFLAGS) -c -MMD -o $@ $<
 
-$(BUILDDIR)/%.o: %.m
+$(BUILDDIR)/%.o: %.m $(BUILDCONFIG_FILES)
 	@echo "===> Obj-c OSX $<"
 	$(Q)$(HOSTCXX) $(CXXFLAGS) $(OBJCFLAGS) -c -MMD -o $@ $<
 
-$(BUILDDIR)/%.o: %.c
+$(BUILDDIR)/%.o: %.c $(BUILDCONFIG_FILES)
 	@echo "===> HOSTCC  $<"
 	$(Q)$(HOSTCC) $(CCFLAGS) -c -MMD -o $@ $<
 
-$(BUILDDIR)/%.o: %.cc
+$(BUILDDIR)/%.o: %.cc $(BUILDCONFIG_FILES)
 	@echo "===> HOSTCXX $<"
 	$(Q)$(HOSTCXX) $(CXXFLAGS) -c -MMD -o $@ $<
 
-$(BUILDDIR)/%.o: %.rc
+$(BUILDDIR)/%.o: %.rc $(BUILDCONFIG_FILES)
 	@echo "===> RES $<"
 #	$(Q)$(WINDRES) --preprocessor "$(HOSTCXX) -E -xc -DRC_INVOKED -MMD -MF $(@:%.o=%.d) -MT $@" -O COFF $< $@
 	$(Q)$(WINDRES) --preprocessor "$(HOSTCXX) -E -xc -DRC_INVOKED -MMD -MT $@" -O COFF $< $@
diff --git config.default.in config.default.in
index 0b2b0770a..4ba845ff4 100644
--- config.default.in
+++ config.default.in
@@ -5,29 +5,7 @@
 
 # this is config.default.in
 
-# allowed backends:
-#BACKEND = allegro
-#BACKEND = gdi
-#BACKEND = opengl
-#BACKEND = sdl
-#BACKEND = sdl2
-#BACKEND = mixer_sdl
-#BACKEND = posix
 BACKEND = @backend@
-
-# color depth either 16 or 0 (the latter needed for server)
-COLOUR_DEPTH = @color@
-
-# architecture specifi flags
-#OSTYPE = amiga
-#OSTYPE = beos
-#OSTYPE = cygwin
-#OSTYPE = freebsd
-#OSTYPE = haiku
-#OSTYPE = linux
-#OSTYPE = mingw
-#OSTYPE = mac
-
 OSTYPE = @os_type@
 
 MSG_LEVEL = 3
diff --git config.template config.template
index a31f43586..8471608c7 100644
--- config.template
+++ config.template
@@ -13,11 +13,9 @@
 #BACKEND = sdl
 #BACKEND = sdl2
 #BACKEND = mixer_sdl
+#BACKEND = mixer_sdl2
 #BACKEND = posix
 
-#COLOUR_DEPTH = 0
-#COLOUR_DEPTH = 16
-
 #OSTYPE = amiga
 #OSTYPE = beos
 #OSTYPE = cygwin
diff --git configure.ac configure.ac
index 21da7ed81..674e4f1c5 100644
--- configure.ac
+++ configure.ac
@@ -120,30 +120,24 @@ AC_ARG_ENABLE([server],
 if test "x$enable_server" != "xno"
 then
 	AC_SUBST(backend, posix)
-	AC_SUBST(color, 0)
 elif test "$ac_cv_header_windows_h" == yes
 then
 	AC_SUBST(backend, gdi)
-	AC_SUBST(color, 16)
 	AC_MSG_WARN([Using GDI backend!])
 elif test "$ac_cv_lib_SDL2_SDL_GetRenderDriverInfo" == yes
 then
 	AC_SUBST(backend, sdl2)
-	AC_SUBST(color, 16)
 	AC_MSG_WARN([Using SDL2 backend!])
 elif test "$ac_cv_lib_SDL_SDL_Init" == yes
 then
 	AC_SUBST(backend, sdl)
-	AC_SUBST(color, 16)
 	AC_MSG_WARN([Using SDL backend!])
 elif test "$ac_cv_lib_allegro_get_desktop_resolution" == yes
 then
 	AC_SUBST(backend, allegro)
-	AC_SUBST(color, 16)
 	AC_MSG_WARN([Using SDL2 backend!])
 else
 	AC_SUBST(backend, posix)
-	AC_SUBST(color, 0)
 	AC_MSG_WARN([No backend found, using server (posix)!])
 fi
 
diff --git makeobj/Makefile makeobj/Makefile
index 98a2bb274..1d3f644d6 100644
--- makeobj/Makefile
+++ makeobj/Makefile
@@ -6,7 +6,7 @@
 CFG ?= default
 -include ../config.$(CFG)
 
-OSTYPES       = beos cygwin freebsd haiku linux mingw mac
+OSTYPES = beos cygwin freebsd haiku linux mingw mac
 
 ifeq ($(findstring $(OSTYPE), $(OSTYPES)),)
   $(error Unkown OSTYPE "$(OSTYPE)", must be one of "$(OSTYPES)")
@@ -53,8 +53,15 @@ endif
 
 ifdef OPTIMISE
   ifeq ($(shell expr $(OPTIMISE) \>= 1), 1)
-    CFLAGS   += -O3 -fno-schedule-insns
-    CXXFLAGS += -O3 -fno-schedule-insns
+    CFLAGS   += -O3
+    CXXFLAGS += -O3
+
+    # clang does not support fno-schedule-insns
+    ifeq ($(findstring clang, $(CXX)),)
+      CFLAGS   += -fno-schedule-insns
+      CXXFLAGS += -fno-schedule-insns
+    endif
+
     ifneq ($(OSTYPE),mac)
       CFLAGS  += -minline-all-stringops
     endif
@@ -90,8 +97,8 @@ ifdef PROFILE
   endif
 endif
 
-CFLAGS   += -Wall -W -Wcast-qual -Wpointer-arith -Wcast-align -Wstrict-prototypes $(OS_INC) $(OS_OPT) $(FLAGS)
-CXXFLAGS += -Wall -W -Wcast-qual -Wpointer-arith -Wcast-align $(OS_INC) $(OS_OPT) $(FLAGS)
+CFLAGS   += -Wall -Wextra -Wcast-qual -Wpointer-arith -Wcast-align -Wstrict-prototypes $(OS_INC) $(OS_OPT) $(FLAGS)
+CXXFLAGS += -Wall -Wextra -Wcast-qual -Wpointer-arith -Wcast-align $(OS_INC) $(OS_OPT) $(FLAGS)
 
 # SOLO_SOURCES contains files which are unique to makeobj;
 # SHARED_SOURCES contains those with the exact same object code in makeobj and simutrans;
diff --git nettools/Makefile nettools/Makefile
index 19d7bd0bc..8bf66318b 100644
--- nettools/Makefile
+++ nettools/Makefile
@@ -36,8 +36,15 @@ endif
 
 ifdef OPTIMISE
   ifeq ($(shell expr $(OPTIMISE) \>= 1), 1)
-    CFLAGS   += -O3 -fno-schedule-insns
-    CXXFLAGS += -O3 -fno-schedule-insns
+    CFLAGS   += -O3
+    CXXFLAGS += -O3
+
+    # clang does not support fno-schedule-insns
+    ifeq ($(findstring clang, $(CXX)),)
+      CFLAGS   += -fno-schedule-insns
+      CXXFLAGS += -fno-schedule-insns
+    endif
+
     ifneq ($(OSTYPE),mac)
       CFLAGS  += -minline-all-stringops
     endif
@@ -73,8 +80,8 @@ ifdef PROFILE
   endif
 endif
 
-CFLAGS   += -Wall -W -Wcast-qual -Wpointer-arith -Wcast-align -Wstrict-prototypes $(OS_INC) $(OS_OPT) $(FLAGS)
-CXXFLAGS += -Wall -W -Wcast-qual -Wpointer-arith -Wcast-align $(OS_INC) $(OS_OPT) $(FLAGS)
+CFLAGS   += -Wall -Wextra -Wcast-qual -Wpointer-arith -Wcast-align -Wstrict-prototypes $(OS_INC) $(OS_OPT) $(FLAGS)
+CXXFLAGS += -Wall -Wextra -Wcast-qual -Wpointer-arith -Wcast-align $(OS_INC) $(OS_OPT) $(FLAGS)
 
 # SOLO_SOURCES contains files which are unique to nettool;
 # SHARED_SOURCES contains those with the exact same object code in nettool and simutrans;
diff --git uncommon.mk uncommon.mk
index 68227e8df..f3db3256f 100644
--- uncommon.mk
+++ uncommon.mk
@@ -10,10 +10,12 @@ OBJS += $(patsubst %, $(BUILDDIR)/$(TOOL)/%-$(TOOL).o, $(basename $(filter-out .
 DEPS := $(patsubst %.o, %.d, $(OBJS))
 DIRS := $(sort $(dir $(OBJS)))
 
+BUILDCONFIG_FILES := ../uncommon.mk Makefile ../config.$(CFG)
+
 # Make build directories
 DUMMY := $(shell mkdir -p $(DIRS))
 
-.PHONY: clean clean-prog
+.PHONY: all clean clean-prog
 
 ifeq ($(VERBOSE),)
   Q = @
@@ -43,19 +45,19 @@ clean:
 	@true
 
 # Source files located in ../
-$(BUILDDIR)/%-$(TOOL).o: ../%.c
+$(BUILDDIR)/%-$(TOOL).o: ../%.c $(BUILDCONFIG_FILES)
 	@echo "===> CC  $<"
 	$(Q)$(CC) $(CCFLAGS) -c -MMD -o $@ $<
 
-$(BUILDDIR)/%-$(TOOL).o: ../%.cc
+$(BUILDDIR)/%-$(TOOL).o: ../%.cc $(BUILDCONFIG_FILES)
 	@echo "===> CXX $<"
 	$(Q)$(CXX) $(CXXFLAGS) -c -MMD -o $@ $<
 
 # Source files located in current directory
-$(BUILDDIR)/$(TOOL)/%-$(TOOL).o: %.c
+$(BUILDDIR)/$(TOOL)/%-$(TOOL).o: %.c $(BUILDCONFIG_FILES)
 	@echo "===> CC  $<"
 	$(Q)$(CC) $(CCFLAGS) -c -MMD -o $@ $<
 
-$(BUILDDIR)/$(TOOL)/%-$(TOOL).o: %.cc
+$(BUILDDIR)/$(TOOL)/%-$(TOOL).o: %.cc $(BUILDCONFIG_FILES)
 	@echo "===> CXX $<"
 	$(Q)$(CXX) $(CXXFLAGS) -c -MMD -o $@ $<