How do I make stuff like this?
GIMP (GNU Image Manipulation Program) is a cross-platform image editor available for GNU/Linux, macOS, Windows and more operating systems. It is free software, you can change its source code and distribute your changes.
Hiding a reticle from gameplay footage?
DaVinci Resolve is an industry-standard tool for post-production, including video editing, visual effects, color correction, and sound design, all in a single application! All creators, hobbyists to professionals, are welcome here. Any topics related to Resolve are welcome here. Not officially affiliated with Blackmagic Design.