@Meego as of now, there are no official confirmation that Mass Effect Legendary Edition will be coming to Stadia.
Make sure to tune in to Stadia news through this community or social media channels, to see if it will be announced in the future (no guarantee)
In the mean time you can always submit feedback through Stadia app to make sure your interest is recorded.
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Stadia Guides are not employed by Google. Opinions are my own.
