Click on the "Games" Tab at the top of the site. Select "All Games" and wait for it to load. Click on the arrow pointing down button next to "Sort by active players" and you will find thousands upon thousands of games that haven't been run recently.
Might as well be most games in existence.
This is the link to see the least ran games: https://www.speedrun.com/games#platform=&orderby=fewestruns&unofficial=off And here are the least active: https://www.speedrun.com/games#platform=&orderby=leastactive&unofficial=off
Do you like resetting? extreme RNG? Do you like Menuing? Do you like spending minimal time actually battling? Do you like borderline animal abuse?
Well do I have the game for you! Check out Monster Rancher 2! Or any of the Monster Rancher games really.