[Quesion] Background keyboard macro

Hello everybody, i was wondering if anyone knows how can i run a macro in a background window so i can keep using my computer. The game im testing it on right now is a Byond game (Made in HTML) and what i want to do is really simple, maybe in the future i'm adding img, or pixl recognize, but by now i just want to press (let's say 'T') as a loop. I read i might need to inject some kind of .dll in the window but i don't know where to start.
I would apreciate if you guys could tell me where to start learning, and wich kind of macro or languaje its more suitable to use.
Thank you for your time (and sorry for my english).

PS. Im quite familiarized with Macros and just a little bit of python, idk if it helps but hope it might

Well I use To do it But i only used it to send mouse clicks for minimized game!
it is easy to learn and
is the way to send keys or mouse clicks to a inactive window
For More info:-Hope This Helps