fullscreen in game overlay / on screen display software for Microsoft Windows

• Playclaw can draw these types of overlay : text, web browser, web cam, hardware stats etc...
  Text can be read from file, at 0.5 seconds interval, supports webcam input from obs virtual cam plugin.
  SDK for version 6 - https://github.com/CyberDemonLord/playclaw6-sdk

• Rivatuner provides shared memory interface to draw text overlay.
  repo - https://github.com/upgradeQ/RTSSSharedMemoryPythonNET

• Cheat Engine can hook directx; example interactive overlay floating window:
  

repo - https://github.com/adhptrh/ed3d

• Reshade can hook - directx,opengl; can draw - current time in overlay,fps,crosshair
  crosshair repo - https://github.com/LouisTakePILLz/reshade-xhair

• Overwolf only for whitelisted apps

• Mangohud not yet working on windows

Dual monitor/screen/display based overlay

OBS Studio supports sending preview to another monitor, so you can grab fullscreen application,
typically a game, compose a scene with overlays, then send it RMB > Fullscreen project > Some monitor.
This also can be used with single monitors, but its requires setting up a virtual(fake) monitor,
for windows required steps described here
Dual monitor tools this software has these features:

• send current application to second monitor - link to manual
• lock mouse in one monitor - link to manual
  To maximise performance of preview - set in Settings>Video>FPS>Integral value to x2 of your monitor Hz.

Directory listing

• /osu - Check osu on how to play flashlight + hidden with overlaying transparent normal replay video.
• /cheatengine - Output health value to txt file repeatedly and then using OBS scripting to set level of opacity filter according to HP value,cheatengine
• pygame_overlay.py - overlay for game OpenSpades running in windowed mode
• overlay.ahk - ahk script to set any window to be non clickable
• x11_pyqt_overlay.py - creates overlay from any window on X11.

See also

transparent fullscreen on-top click-through WebKit web view, for making cool desktop HUDs