If I want to start a run on a game with both the game and LiveSplit open, I need to click on LiveSplit, start the run, then click back on the game to gain control. Can I start the timer without clicking the window, and simultaneously starting the game, without an autosplitter?

Look for Global Hotkeys in the LiveSplit's settings

I don't see any problems here, maybe you need to improve this one.

what?

i already found the fix which was global hotkeys, its fine now