SDL is Simple Direct-media Layer (I think) and is a low level c++ frame work for writing games and multimedia applications. I wrote everything from the main loop to sprite animation classes, smoothing, serialisation, menus etc. etc. Great fun to have total control but also a pain, so Godot is a joy though I might investigate c++ to supplement gdscript as I'm not really into the python style (yet). Have a look at SDL here https://www.libsdl.org/