I think the best idea to do what you're looking for is to find a message board as tightly focused on a particular game as possible, and it has to have an active community.
Some years ago I got really into Diablo 2, but instead of online I was doing it single player. I had my usual characters but I also had a few that had to find all their own gear. Now that's a challenge - try beating hell mode solo the whole way without taking ANY gear found by other characters. Or playing an unconventional build.
I once took on a community challenge to do a melee Sorceress. Someone donated an endgame weapon and I used other gear I had found to make it almost all the way through the game.
Basically, an active community of enthusiasts for a particular game can give you some great ideas for how to play the game in new and interesting (and challenging) ways. The problem is it's not so easy to find. I'm not sure of a KOTOR-focused board even exists, or even if it did, if it's still active after all this time. I mean, there are only so many ways you can play KOTOR. You'd have better luck with games that are pretty new, like the Mass Effect or newer Fallout games, or with ones that have stood the test of time, like Diablo.
Thing is, older games were actually really short, but newer games will take about the same amount of time no matter who's playing. You can complete a Mario game in well under an hour if you know exactly what to do, but it's impossible to complete games like Call of Duty or Mass Effect in less than several hours. There are cutscenes, scripted sequences, and no real shortcuts. So the speedrun community probably won't be interested in newer games.