Keep Windows screen on, no mater what weird-and-hidden power configs it uses.

awake.c

#define WIN32_LEAN_AND_MEAN
#include <Windows.h>

#ifdef MB_DEBUG
  #define INTERVAL (500)
#else
  #define INTERVAL (30 * 1000)
#endif

#ifdef MB_DEBUG
void __cdecl popup_num(const DWORD val)
{
	wchar_t msg[300] = { 0 };
	wsprintfW(msg, L"%08X", val);
	MessageBoxW(0, msg, L"", MB_OK);
}
#endif

int __stdcall wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int cmdShow)
{
	while(TRUE)
	{
		EXECUTION_STATE esRet = SetThreadExecutionState(ES_CONTINUOUS | ES_DISPLAY_REQUIRED | ES_AWAYMODE_REQUIRED);
		#ifdef MB_DEBUG
		popup_num(esRet);
		#endif

		Sleep(INTERVAL);
	}

	SetThreadExecutionState(ES_CONTINUOUS);
	return 0;
}

awake.make

#CC_DEFS = /DMB_DEBUG

CC_ARGS = /nologo /utf-8 /c /W3 /Ox /Zo- /GL /MT
LD_ARGS = /nologo /ltcg
LD_LIBS = user32.lib

all: awake.exe

awake.exe: awake.obj
	link $(LD_ARGS) /out:$@ $** $(LD_LIBS) 

awake.obj: awake.c
	cl $(CC_ARGS) $(CC_DEFS) /Fo$@ $**

.PHONY: run

run: awake.exe
	start "" /d C: /low $**

.PHONY: clean

clean:
	del /f awake.obj
	del /f awake.exe