I just joined this site a few days ago because i wanted to speedrun some PC games i have, but i've run into a problem. All the runs i've recorded so far were done with the built-in 'Microsoft Game Capture', which has a major limitation of only recording one window at a time. I've tried OBS and XSplit, but both seem to affect the game's running speed noticeably more than Microsoft Game Capture. I have a screenshot of the final timer for each run saved in image form (livesplit btw), and my main question here is this: Is it okay for me to submit a run that shows only gameplay, until the end of the run in which i show the livesplit screenshot of the final time?

You’ll need to check the rules of the game(s) that you’re running. Each game on the site has its own rules, so you’ll need to check the rules for each on to make sure they don’t have a requirement for a timer to be shown in the video. If you still have any questions or if the rules don’t say anything about the timer, you can ask the mods of the game as well if they have any rules about it.

Timer usually won’t be required, except maybe for a few PC games that use any autosplitters or anything like that.

That answer pretty much sums it up well. The main reason i was asking was just in case there was some site-wide rule i didn't know about. Also, i think it's worth mentioning that the games i've done runs of so far don't even have a category yet.