you can only do chapter and full game runs, however, there is a individual chamber website. https://board.portal2.sr/ if you mean a single chapter run, just click the leaderboards button, click the submit run button, then put the link of the youtube video, time, and submit it.
yeah board.portal2.sr is for challenge mode but only top 200 times are displayed there and if you get top 200 times in challenge mode it automatically updates if you're signed in with steam (only top 100 times require video or demos i think) edit: now top 500 are displayed and top 200 need proof
The Challenge Mode leaderboards have changed to top 500 as of yesterday!
SAR version 1.14.2 just dropped, which improves the speedrun timer HUD (sar_sr_hud), ghost sync countdowns, and more. You can find the full release notes on the SAR github, and as always you have 1 week to update.
We're also clarifying the ruling of sar_hud_precision for Least Portals. In all other
