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I looked around for some terms but could not see what I want to suggest. If it exists please point me to it to vote it up.

In Steam I can select a game's version by selecting an experimental branch of the game to install. Factorio is one such example where the versions are several stable versions and plenty experimental versions of the last branch.
GOG Galaxy 2.0 seems to just launch what is already installed without the option to modify this version, so it launches whatever is already installed by Steam.

I would like to be able to select experimental versions of the games (where available) from within GOG Galaxy 2.0 in a continued effort to control Steam games without having to go to Steam.