@elim Which version of Chrome are you in right now? There's also another user experiencing the same thing. Even though Chrome says he's on the latest update, turns out it's not. I originally had the same issue, but was able to launch Stadia games after getting it to version 78.0.3904.106 (Official Build) (64-bit)
Here's the link to the discussion:
@elim That's newer than mine (prob just different versioning from Linux to Chromebook) but looks like on the same level. Were you actually able to launch a game, then it just kept spinning, or was it actually blocking you from launching the game (what happened to me before upgrading)?
@Ivan On windows, I can click the game, and it acts like it's going to start, but then I just get the 'Checking your connection...' which hangs there for a few minutes, and finally only gives me an option to go back to the main menu. On linux, it just tells me to update Chrome, and ends there. This reddit thread outlines the same issue: https://old.reddit.com/r/Stadia/comments/dyshbf/stuck_in_checking_your_connection_i_cant_launch/
@elim Yeah not sure what's going on then.. I'm assuming your Chrome version on Windows is also on the latest version? If yes, I don't know what's going on.. I had no issue launching games on Chrome PC/Chromebook.. Hopefully someone else will be able to help you out.
I stumbled on another post, which seems to solve the issue, but it is not an acceptable solution. I disabled ublock origin for the site originally, but hadn't disabled it entirely. Disabling it entirely seems to resolve the issue. However, a friend who also has ublock origin installed does not have the same issue.
Opening in an incognito window resolved the issue for me. Going to have to figure out which extension has things mucked up: probably adblocker.
UPDATE: it was my VPN Chrome Extension -- even though I wasn't currently using it. Disabled it and Stadia is working without incognito.